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The effect of Co and Ce codoping in CuIn0.9CexCo0.1−xTe2
Journal Pre-proofs Research articles The effect of Co and Ce codoping in CuIn0.9CexCo0.1-xTe2 Tai Wang, Yongquan Guo, Cong Wang, Shuowang Yang PII: DOI: Reference:
S0304-8853(19)33329-3 https://doi.org/10.1016/j.jmmm.2020.166506 MAGMA 166506
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Journal of Magnetism and Magnetic Materials
Received Date: Revised Date: Accepted Date:
20 September 2019 6 January 2020 22 January 2020
Please cite this article as: T. Wang, Y. Guo, C. Wang, S. Yang, The effect of Co and Ce codoping in CuIn0.9CexCo0.1-xTe2, Journal of Magnetism and Magnetic Materials (2020), doi: https://doi.org/10.1016/j.jmmm. 2020.166506
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The effect of Co and Ce codoping in CuIn0.9CexCo0.1-xTe2 Tai Wang, Yongquan Guoa), Cong Wang, Shuowang Yang School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
Abstract The codoped dilute magnetic semiconductor CuIn0.9CexCo0.1-xTe2 has been successfully prepared by arc melting and vacuum solid-state reaction technologies. CuIn0.9CexCo0.1-xTe2 crystallizes into body centered tetragonal structure with a space group of I42d. The codoping of Co and Ce induces the room temperature ferromagnetism in CuIn0.9CexCo0.1-xTe2. The magnetization of CuIn0.9CexCo0.1-xTe2 are enhanced by codoping Ce and Co into CuInTe2, which is ascribed to the exchanging interaction between 4f electron of Ce and 3d electron of Co. Magnetic measurements show that Co influences mainly on the saturation magnetic moment of CuIn0.9CexCo0.1-xTe2. The high doping ratio of Co and Ce is beneficial for increasing saturation magnetization and the magnetic transformation temperature. Codoping Ce and Co into CuInTe2 can adjust the light absorption bandgap from 0.92eV to 1.08eV, which is slightly higher than that of CuInTe2. It shows that the light absorption bandgap can be refined by controlling Co/Ce ratio for the potential application of solar cell material.
Key Words: Crystal structure; Co/Ce co-doping; Magnetic properties; Diluted magnetic semiconductor; Bandgap
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1. Introduction The dilute magnetic semiconductor (DMS) has attracted a great deal of interest in recent years due to its special characteristics of room temperature ferromagnetism [1-5] and the potential application of spintronic devices [3, 6-9]. 3d transition metal (TM) doping into semiconductor could cause significantly magnetic transition [4, 8, 10-13]. In a usual antiferromagnetic (AFM) material, the net magnetic moment is compensated by the reversal of a spin-density wave, where the electrons with spin up and spin down are identical. These effects cause no spin polarization of the conduction electrons at the Fermi level. However, the dual doping of a suitable 3d TM pair with total equivalent electrons at III site of I-III-VI2 chalcopyrite semiconductor predicts a zero net magnetic moment[14, 15]. As a result, a full spin polarization of the conduction electrons is obtained at the Fermi level, where the host semiconductor is doped by at least two types of magnetic atoms of equal concentration. Furthermore, the physical behavior of magnetic system is deeply influenced by the 4f electrons of rare earth element arising from Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, Kondo effect and crystal-field effects, which induces many phenomena such as topological state, heavy-fermion and quantum critical state, magnetic or multipolar ordering. The magnetic ions doped CuInTe2 shows various magnetic properties. Moreover, the previous studies show that the magnetic states of rare earth and TM are strongly related to the external field due to the spin orientation of 3d transition metal and 4f rare earth [16, 17]. In our previous study of Ce doped CuInTe2, the mixture valence state of Ce ions with 4+ and 3+ is confirmed to coexist in CuInxCe1-xTe2 by X-ray Photoelectron Spectroscopy (XPS) and Raman scattering spectrum measurement, Ce ion with 4+ produces one electron and induces the formation of ntype semiconductor[18]. Co doped CuInTe2 semiconductor with chalcopyrite structure shows ferromagnetic characteristics with a Curie temperature around 980 K and p-type semiconductor with a carrier concentration of 2.4 × 1018/cm3 [19]. Based on these previous studies, the designation of CuIn0.9CexCo0.1-xTe2 matches the room temperature dilute magnetic semiconductor, i.e. single phase, diluting magnetic properties by codoping 3d transition metal Co and 4f rare earth Ce into CuInTe2 with 3.33 at % of occupation ratio at In site, room 2
temperature ferromagnetism, and semiconducting characteristics. The codoping effect of Co and Ce on magnetic property and light absorption bandgap in CuIn0.9CexCo0.1-xTe2 is systematically investigated due to the possible exchanging interaction of 3d transition metal Co and 4f rare earth Ce . 2. Material and methods The nominal compositions CuIn0.9CexCo0.1-xTe2 (x =0.02, 0.04, 0.06, 0.08) with purity more than 99.99 wt% for each raw material were prepared using arc melting and vacuum solid state reaction technologies under atmosphere of high pure argon gas. Each sample was remelted for four times for ensuring the homogeneity. The extra Te is prepared for compensation during the melting, furthermore, the tellurium ingredient was added for melting with the precursor Cu-In-Ce-Co alloys to reduce the loss of Te element. The phase structure of CuIn0.9CexCo0.1-xTe2 was measured using Rigaku G/max 2500 Xray diffractometer with Cu Kα1 radiation and power of 8 kW. The field emission scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) were used to investigate the surface morphologies and check the element component of CuIn0.9CexCo0.1-xTe2. The field dependence of magnetization for CuIn0.9CexCo0.1-xTe2 at room temperature was measured by vibrating sample magnetometer (VSM) under the applied fields ranging from 0 to 30 kOe. The thermomagnetic properties were measured by VSM in the temperature range from 300-800K under an applied field of 50Oe. The wavelength dependence of light absorption rate for CuIn0.9CexCo0.1-xTe2 was measured on a Shimadzu 2450 UV-Vis spectrophotometer with scanning range of 300-800nm and scanning step of 0.5nm/s. 3. Result and Discussion The X-ray diffraction analyses show that CuIn0.9CexCo0.1-xTe2 (x=0.02, 0.04, 0.06, 0.08) are single phase with space group of I42d. X-ray diffraction patterns of CuInTe2 and CuIn0.9CexCo0.1-xTe2 are refined by a Rietveld structural refinement technology, as presented in Fig 1. The observed and calculated X-ray diffraction patterns are denoted by red symbols of 3
“+” and green lines, respectively. The vertical blue bars denote the diffraction peak positions, and the lowest lines indicate the differences of diffraction intensities between the observed and calculated XRD patterns. The diffraction peaks of CuIn0.9CexCo0.1-xTe2 can been indexed with a body centered tetragonal structure as listed in appendix. The planar indices are acceptable since both the values of Merit factor M and the Smith factor F are larger than 10. The refined structural parameters of CuIn0.9CexCo0.1-xTe2 are presented in Table 1. The pattern residual factor Rp and the weighted residual pattern factor Rwp are within 10%, which indicate the reliability of the refined results. The lattice parameters are sensitive to the doping contents of Ce and Co，the high ratio of Ce/Co at the In site (4b) causes the lattice expansion and drives Te movement along the a axis. Table 2 lists the bond length and bond angles in CuIn0.9CexCo0.1xTe2,
It shows that the high Ce/Co ratio at In site causes the increase of Cu-Te bond and the
decrease of (In,Co,Ce)-Te bond, and (In,Co,Ce)-Te-(In,Co,Ce) bond-angle also show a regular change with increasing Ce/Co doping ratio. These phenomena are ascribed to the size effect at In site since the order of atomic radius is Ce(1.82 Å), In(1.66 Å) and Co(1.26 Å). SEM morphologies and EDS spectra of CuIn0.9CexCo0.1-xTe2 powers are presented in Fig 2. The grains are apparently in size of micrometer scale with irregular shape. However, the grains tend to be small and disperse uniformly with increasing Ce/Co doping ratio, which illustrates that Ce could refine grain and disperse uniformly. The element components are slightly deviation from the nominal CuIn0.9CexCo0.1-xTe2. The content of Te is slightly lower than the normal composition ones, it implies be due to the volatilization during the melting preparation, and the low Ce/Co doping ratio is ascribed to the incompletion fusion into the basal body. Fig 3 shows that the typical field-dependence of magnetization for CuInTe2, CuIn0.9Co0.1Te2 and CuIn0.9Ce0.02Co0.08Te2 at room temperature under the applied field range of 0-30 kOe. Based on our previous study[19], CuInTe2 shows diamagnetic characteristics with susceptibility around 10-5 due to the diamagnetisms of Cu, In and Te. Co doping into CuInTe2 induces a ferromagnetic transition, and the ferromagnetism can be interpreted by the double exchange mechanism proposed by Zener, the ferromagnetic ordering originates from the itinerate electrons hoping along Co2+-Te-Co3+, one 4p electron of Te is hoping into the vacant 4
eg orbital Co3+(t2g6eg0), and followed by eg electron of Co2+(t2g6eg1) with the same spin direction of 4p electron is hopping into the 4p orbital of Te. Furthermore, the RKKY effect on Ce3+ also contributes to the magnetism of CuIn0.9CexCo0.1-xTe2. Combining the experimental results and above magnetic characters, a mixture magnetism model, which is based on the Ref [17] and [20], is proposed to fit the experimental data, as listed in Eq.1.
( ) 𝑎
(1)
𝑀 = 𝑀𝑠𝐸𝑥𝑝 ― 𝐻 ―𝜒𝐻
Where the first item represents the contribution to magnetization of ferromagnetic phase: MS, H are the saturation magnetization and applied field, respectively; a is coefficient of the applied field and the ratio of a/H shows the tendency of approach to saturation moment. This equation can be regarded as a simplified magnetizing model proposed by Weiss[21] since this equation 𝑎1
𝑎2
𝑎3
can be rewritten by Taylor series expansion algorithm as: M = 𝑀𝑠(1 ― 𝐻1 + 𝐻2 ― 𝐻3⋯). The second item corresponds the contribution of diamagnetism, where χ and H are susceptibility and applied field. The symbol of minus represents the adverse contribution from diamagnetism to the mixture magnetism of CuIn0.9CexCo0.1-xTe2. Fig. 4 shows the fitted field dependence of magnetizations for CuIn0.9CexCo0.1-xTe2 at room temperature, and the fitting parameters are presented in Table 3. The fitted results illustrate the room temperature ferromagnetism of CuIn0.9Ce0.08Co0.02Te2 and CuIn0.9Ce0.06Co0.04Te2, while CuIn0.9CexCo0.1-xTe2 with low Ce/Co doping ratio exhibits mixture characteristics of ferromagnetism and diamagnetism. The saturation magnetization increases with reducing Ce/Co doping ratio due to the substitution of the strong magnetic of Co for Ce. According to the fitting results, the saturation magnetization of CuIn0.9CexCo0.1-xTe2 mainly depends on ferromagnetic characteristics. Comparing to the saturation magnetization of 0.2185 emu/g in CuIn0.9Co0.1Te2 [19], The magnetizations of CuIn0.9Ce0.02Co0.08Te2 and CuIn0.9Ce0.04Co0.06Te2 show significant enhancement by codoping of Ce and Co, which might be ascribed to the exchanging interaction between 4f electron of Ce and 3d electron of Co. The saturation magnetization is closely related to the bond consisting of closest magnetic ions[22], and the closest magnetic bond distance 𝐷𝐶𝑜,𝐶𝑒 ― 𝐶𝑜,𝐶𝑒 depends on the (Ce,Co)-Te bond distance of 𝐷𝐶𝑜,𝐶𝑒 ― 𝑇𝑒 and (Co,Ce)-Te-(Co,Ce) bond angle 𝜃(Co,Ce) ― Te ― (Co,Ce) and follows Eq.2 as below: 5
𝐷𝐶𝑜,𝐶𝑒 ― 𝐶𝑜,𝐶𝑒 = 2𝐷𝐶𝑜,𝐶𝑒 ― 𝑇𝑒sin (𝜃(Co,Ce) ― Te ― (Co,Ce)/2)
(2)
The relationship between the saturation magnetization and the distortion degree can be revealed by the equation as below: M = 𝑀0 + 𝐾𝑚∆𝐷𝐶𝑜,𝐶𝑒 ― 𝐶𝑜,𝐶𝑒
(3)
where M0 is the intrinsic magnetization; ΔDCo,Ce-Co,Ce is the bond length difference, which is defined as ΔDCo,Ce-Co,Ce =|DCo,Ce-Co,Ce(CuIn0.9CexCo0.1-xTe2) –DIn-In(CuInTe2)|; Km is the constant. This model reveals that the correlation between lattice distortion and saturation magnetization by altering the magnetic interaction along (Co,Ce)-(Co,Ce) bond. The ferromagnetic order is enhanced with increasing lattice distortion. The fitted data agree well with the observed ones as shown in Fig 5. The magnetic state of cobalt is variation and shows low spin state at low temperature and high spin state at high temperature, thus, Co spin state is unstable due to its spin rotation driven by increasing temperature[19]. Owing to the room temperature ferromagnetism of CuIn0.9CexCo0.1-xTe2, the field cooling (FC) thermomagnetic curve is measured in temperature range from 300K to 800K for demining their Curie temperatures, as presented in Fig 6. It shows that CuIn0.9CexCo0.1-xTe2 exhibits significant difference for the temperature dependence of magnetization. The magnetizations of CuIn0.9CexCo0.1-xTe2 increase significantly and magnetic transformation temperature tends to be more prominent with increasing Co/Ce doping ratio. For CuIn0.9Ce0.02Co0.08Te2, a magnetic transformation from antiferromagnetic to ferromagnetic is observed at 312K, and the Curie temperature is around 783K. However, a drop is observed around 446K, which might be due to the spin-reorientation as observed in Nd2Fe14C and Ce(Co, Ga)13 and abnormal change of anisotropic parameter k1 [23]. For CuIn0.9Ce0.02Co0.08Te2, the transition originates from the spin rotation at Co sublattice with increasing temperature, since 4f spin rotation of Ce induces magnetostriction due to a non-symmetric crossing configuration in 4f orbital. The exchanging interaction between the Ce- and Co-sublattice can be interpreted with the R 4f band polarization (R= rare earth), which can be described by the 4f-3d (R- T) interaction. The UV-Vis absorption spectra of CuIn0.9CexCo0.1-xTe2 powders are shown in Fig. 4. As the absorbance Ab is determined by the following equation[18]： 6
𝐴𝑏 = 𝛼𝑐𝑙
(4)
where α, c and l are absorption coefficient, concentration of absorption material, and thickness of the liquid layer, respectively. c and l can be determined experimentally and the absorbance Ab is proportion to the absorption coefficient α. Therefore, the value of absorption coefficient α can be determined based on the absorption data. The band gap Eg of light absorption is obtained based on Eq. 5 [24]: 𝛼ℎ𝜈 = 𝐴(ℎ𝜈 ― 𝐸𝑔)𝑛
(5)
where α and ν are the absorption coefficient and photon frequency respectively; A and n are constants. A depends on temperature and photon energy, and the values of the exponent n, in this case, should be 1/2 due to the direct transition of CICCT compounds. Combined with Eq. 4, the equation to determine the optical energy band gap Eg can be written as (𝐴𝑏ℎ𝜈)2 = 𝐴2𝑐2𝑙2(ℎ𝜈 ― 𝐸𝑔)
(6)
A plot of (Abhν)2 versus hν is expected to be a straight line whose intercept on the X axis gives the optical band gap Eg value for CICCT is determined by extrapolating the linear portion of the curve to the X axis, the cross point in the X axis corresponds to Eg value. The light absorption bandgaps of CICCT are in the range of 0.92eV-1.08eV, as shown in Fig.7, the bandgap is slightly broader than that of CuInTe2 (0.91eV-1.0eV). However, According to previous reports, the bandgap of CuIn0.9Ce0.1Te2 is 1.28 eV[18]. It illustrates that the bandgap can be adjusted by codoping of magnetic Co and Ce due to spin-controlled transport mechanism.
4. Conclusions The dilute magnetic semiconductor CuIn0.9CexCo0.1-xTe2 are prepared by arc melting and vacuum solid-state reaction technologies. CuIn0.9CexCo0.1-xTe2 crystallizes into body centered 7
tetragonal structure with a space group of I42d. The codoping of Co and Ce induces the room temperature ferromagnetism in CuIn0.9CexCo0.1-xTe2. The magnetization is increasing with codoping Ce and Co into CuInTe2 due to the exchanging interaction between 4f electron of Ce and 3d electron of Co, which illustrates that both of Co and Ce contributes to the magnetic properties. Magnetic measurements show that Co has the dominating influence on the saturation magnetic moment of CuIn0.9CexCo0.1-xTe2. The high doping ratio of Co and Ce is beneficial for increasing saturation magnetization and the magnetic transformation temperature. (Ce, Co) codoping into CuInTe2 can change the light absorption bandgap from 0.92eV to 1.08eV in CuIn0.9CexCo0.1-xTe2, which is slightly higher than that of CuInTe2. It shows that the light absorption bandgap can be refined by controlling Co/Ce ratio for the potential application of solar cell material.
Acknowledgments This work was supported by the National Key R&D Program of China (2018YFB0905600), the Fundamental Research Funds for the Central Universities of China (2019QN085)
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Figure captions Figure 1. The refined and observed XRD patterns of CuIn0.9CexCo0.1-xTe2 dilute magnetic semiconductors. Figure 2. SEM morphologies and EDS patterns of CuIn0.9CexCo0.1-xTe2 powders, where x=0.02 in 2 a), x=0.04 in 2 b), x=0.06 in 2c), and x=0.08 in 2d) Figure 3. The field dependence of magnetization for CuInTe2, CuIn0.9Co0.1Te2 and CuIn0.9Ce0.02Co0.08Te2 Figure 4. The fitted M-H curves of CuIn0.9CexCo0.1-xTe2 dilute magnetic semiconductor. Figure 5. The fitted magnetic moments of CuIn0.9CexCo0.1-xTe2 at room temperature. Figure 6. The temperature dependence of magnetization for CuIn0.9Ce0.02Co0.08Te2 and CuIn0.9Ce0.08Co0.02Te2 with field cooling mode. Figure 7. UV-Vis absorption spectra of CuIn0.9CexCo0.1-xTe2 dilute magnetic semiconductor
12
Table 1. Rietveld refined structural parameters of CuIn0.9CexCo1-xTe2 Paramete rs a(Å) c(Å) V(Å3) Cu(4a) In(4b) Ce(4b) Co(4b) Te Rwp Rp
CuIn0.9Ce0.02Co0.0 8Te2 6.193(6) 12.411(6) 476.1174 (0,0,0) (0,0,1/2) (0,0,1/2) (0,0,1/2) (0.22032,1/4,1/8) 7.824% 5.862%
CuIn0.9Ce0.04Co0.0 6Te2 6.194(2) 12.414(5) 476.3209 (0,0,0) (0,0,1/2) (0,0,1/2) (0,0,1/2) (0.22057,1/4,1/8) 8.636% 6.226%
13
CuIn0.9Ce0.06Co0.0 4Te2 6.195(1) 12.415(1) 476.4824 (0,0,0) (0,0,1/2) (0,0,1/2) (0,0,1/2) (0.22127,1/4,1/8) 9.770% 7.243%
CuIn0.9Ce0.08Co0.0 2Te2 6.195(5) 12.416(9) 476.6130 (0,0,0) (0,0,1/2) (0,0,1/2) (0,0,1/2) (0.22213,1/4,1/8) 9.809% 6.830%
Table 2. The bond length and bond angle of CuIn0.9CexCo0.1-xTe2 CuInTe2 Band length(Å)
Bond angles(°)
CuIn0.9CexCo00.1 -xTe2
Cu-Te
In-Te
In-Te-In
Cu-TeCu
Cu-TeIn
Te-InTe
Te-CuTe
x=0.02
2.5818
2.7935
103.064
116.193
109.209
107.963
111.166
109.046
112.531
106.074
116.137
109.217
107.978
111.155
115.971
109.047 109.229
112.500 108.012
106.154 111.113
115.771
109.067 109.246
112.432 108.056
106.236 111.064
109.084
112.341
106.330
x=0.04
x=0.06
x=0.08
2.5832
2.5858
2.5886
2.7932
2.7908
2.7875
103.417
103.554
103.726
14
Table 3. The fitted magnetizing parameters of CuIn0.9CexCo0.1-xTe2
R2 Value Ms(emu/g ) a(KOe) χ(emu/g• KOe) Standard Error of Ms(emu/g ) Standard Error of μ/KBT(K Oe) Standard Error of χ(emu/g• KOe)
CuIn0.9Ce0.02Co0. 08Te2
CuIn0.9Ce0.04Co0. 06Te2
CuIn0.9Ce0.06Co0. 04Te2
CuIn0.9Ce0.08Co0. 02Te2
0.99239 0.5776
0.98861 0.36391
0.97973 0.20217
0.98021 0.15001
1.6300 0.0025
1.92478 0.00227
1.5113 8.80487E-4
1.92919 8.858E-4
0.00205
0.00172
0.00107
9.2619E-4
0.01323
0.01858
0.01928
0.02424
7.88541E-5
6.40861E-5
4.1911E-5
3.43853E-5
15
Appendix A Table A1. The planar indices of CuIn0.9Ce0.02Co0.08Te2 H
K
L
sin2θobs
sin2θcalc
1 1 2 0.046588 0.046503 1 0 3 0.050335 0.050297 2 0 0 0.062065 0.062098 2 1 1 0.081686 0.081486 2 1 3 0.112532 0.112395 2 2 0 0.124255 0.124196 3 0 1 0.143754 0.143584 3 1 2 0.170786 0.170699 2 2 4 0.186155 0.186013 3 2 1 0.205619 0.205682 3 2 3 0.236506 0.236591 4 0 0 0.24834 0.248392 4 1 1 0.267721 0.26778 3 1 6 0.294253 0.294334 3 2 5 0.298314 0.298408 4 2 4 0.372191 0.372307 5 0 1 0.39199 0.391976 M(17)=20 F(17)=11 a=6.182(1)Å c=12.392(3)Å V=473.62Å3
16
2θobs
2θcalc
24.93 25.93 28.852 33.214 39.201 41.28 44.562 48.82 51.12 53.931 58.198 59.78 62.318 65.701 66.211 75.19 77.525
24.907 25.92 28.86 33.172 39.176 41.27 44.534 48.807 51.099 53.94 58.209 59.787 62.326 65.712 66.223 75.204 77.523
Table A2. The planar indices of CuIn0.9Ce0.04Co0.06Te2 H
K
L
sin2θobs
sin2θcalc
2θobs
2θcalc
1 1 2 2 2 2 3 3 2 3 3 4 4 3 3 4 5
1 0 0 1 1 2 0 1 2 2 2 0 1 1 2 2 0
2 3 0 1 3 0 1 2 4 1 3 0 1 6 5 4 1
0.046523 0.050327 0.062061 0.081547 0.112278 0.12413 0.143627 0.170676 0.186093 0.205522 0.236476 0.248308 0.267649 0.294211 0.298272 0.372132 0.391863
0.046491 0.050287 0.062076 0.081458 0.112363 0.124152 0.143534 0.170643 0.185962 0.20561 0.236515 0.248304 0.267686 0.294263 0.298325 0.37219 0.391838
24.912 25.928 28.851 33.185 39.155 41.259 44.541 48.803 51.111 53.917 58.194 59.776 62.309 65.696 66.206 75.183 77.51
24.903 25.917 28.855 33.167 39.17 41.262 44.526 48.798 51.092 53.93 58.199 59.775 62.314 65.703 66.212 75.19 77.507
M(17)=34 F(17)=18 a=6.183(2)Å c=12.393(1)Å
V=473.82Å3
17
Table A3. The planar indices of CuIn0.9Ce0.06Co0.04Te2 H
K
L
SST-OBS
SST-CALC
2TH-OBS
2TH-CALC
1 1 2 2 2 2 3 3 2 3 3 4 2 3 3 4 5
1 0 0 1 1 0 0 1 2 2 2 0 1 1 2 2 0
2 3 0 1 3 4 1 2 4 1 3 0 7 6 5 4 1
0.046479 0.050294 0.062037 0.08142 0.112317 0.123813 0.143401 0.170365 0.18578 0.205257 0.236297 0.247731 0.266932 0.29417 0.298188 0.372014 0.391481
0.046471 0.050292 0.062022 0.081392 0.112313 -0.123864 -0.143414 -0.170515 -0.185886 -0.205436 -0.236357 -0.248087 0.266919 -0.294199 -0.298199 0.371951 -0.391501
24.9 25.919 28.845 33.159 39.162 41.204 44.504 48.756 51.065 53.879 58.17 59.699 62.216 65.691 66.195 75.169 77.465
24.898 25.919 28.842 33.153 39.161 41.212 44.506 48.779 51.08 53.905 58.178 59.747 62.215 65.695 66.196 75.161 77.467
M(17)=27 F(17)=17 a=6.185(9)Å c=12.389(8)Å
V=474.11Å3
18
Table A4. The planar indices of CuIn0.9Ce0.08Co0.02Te2 H
K
L
sin2θobs
sin2θcalc
2θobs
2θcalc
1 1 2 2 2 2 3 3 2 3 3 4 4 3 3 2 5
1 0 0 1 1 2 0 1 2 2 2 0 1 1 2 2 0
2 3 0 1 3 0 1 2 4 1 3 0 1 6 5 8 1
0.046492 0.050377 0.062097 0.081529 0.112307 0.123915 0.1435 0.170402 0.185697 0.205281 0.236088 0.247891 0.267111 0.293756 0.297892 0.371132 0.390909
0.04643 0.050243 0.061972 0.081326 0.112215 -0.123944 0.143298 0.170374 -0.185722 0.20527 -0.236159 0.247888 -0.267242 -0.293931 -0.297937 0.371056 -0.391185
24.904 25.941 28.86 33.181 39.16 41.221 44.52 48.761 51.053 53.883 58.141 59.721 62.239 65.639 66.158 75.064 77.398
24.887 25.906 28.83 33.139 39.143 41.226 44.487 48.757 51.056 53.881 58.151 59.72 62.256 65.661 66.164 75.055 77.43
M(17)=18 F(17)=10 a=6.188(4)Å c=12.396(3)Å
V=474.74Å3
19
We have read and have abided by the statement of ethical standards for manuscripts submitted to Journal of Magnetism and Magnetic Materials. We declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper (MAGMA_2019_3094_R1).
20
Declaration of interests
☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
21
Highlights
1. Ferromagnetism with slight diamagnetism character at room temperature for CuIn0.9CexCo0.1-xTe2 2. Enhancement on magnetism with electron interaction of Ce4f and Co3d when compared to Cu(In, Co)Te2 3. Higher Co/Ce doping ratio leads to a greater magnetism and more prominent magnetic transformation 4. Adjusting light absorption bandgap slightly higher than CuInTe2.
22
S0304-8853(19)33329-3 https://doi.org/10.1016/j.jmmm.2020.166506 MAGMA 166506
To appear in:
Journal of Magnetism and Magnetic Materials
Received Date: Revised Date: Accepted Date:
20 September 2019 6 January 2020 22 January 2020
Please cite this article as: T. Wang, Y. Guo, C. Wang, S. Yang, The effect of Co and Ce codoping in CuIn0.9CexCo0.1-xTe2, Journal of Magnetism and Magnetic Materials (2020), doi: https://doi.org/10.1016/j.jmmm. 2020.166506
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© 2020 Elsevier B.V. All rights reserved.
The effect of Co and Ce codoping in CuIn0.9CexCo0.1-xTe2 Tai Wang, Yongquan Guoa), Cong Wang, Shuowang Yang School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
Abstract The codoped dilute magnetic semiconductor CuIn0.9CexCo0.1-xTe2 has been successfully prepared by arc melting and vacuum solid-state reaction technologies. CuIn0.9CexCo0.1-xTe2 crystallizes into body centered tetragonal structure with a space group of I42d. The codoping of Co and Ce induces the room temperature ferromagnetism in CuIn0.9CexCo0.1-xTe2. The magnetization of CuIn0.9CexCo0.1-xTe2 are enhanced by codoping Ce and Co into CuInTe2, which is ascribed to the exchanging interaction between 4f electron of Ce and 3d electron of Co. Magnetic measurements show that Co influences mainly on the saturation magnetic moment of CuIn0.9CexCo0.1-xTe2. The high doping ratio of Co and Ce is beneficial for increasing saturation magnetization and the magnetic transformation temperature. Codoping Ce and Co into CuInTe2 can adjust the light absorption bandgap from 0.92eV to 1.08eV, which is slightly higher than that of CuInTe2. It shows that the light absorption bandgap can be refined by controlling Co/Ce ratio for the potential application of solar cell material.
Key Words: Crystal structure; Co/Ce co-doping; Magnetic properties; Diluted magnetic semiconductor; Bandgap
a)
author to whom correspondence should be addressed Email: [email protected]; Tel:
+86-10-61772853; Fax: +86-10-61772383
1
1. Introduction The dilute magnetic semiconductor (DMS) has attracted a great deal of interest in recent years due to its special characteristics of room temperature ferromagnetism [1-5] and the potential application of spintronic devices [3, 6-9]. 3d transition metal (TM) doping into semiconductor could cause significantly magnetic transition [4, 8, 10-13]. In a usual antiferromagnetic (AFM) material, the net magnetic moment is compensated by the reversal of a spin-density wave, where the electrons with spin up and spin down are identical. These effects cause no spin polarization of the conduction electrons at the Fermi level. However, the dual doping of a suitable 3d TM pair with total equivalent electrons at III site of I-III-VI2 chalcopyrite semiconductor predicts a zero net magnetic moment[14, 15]. As a result, a full spin polarization of the conduction electrons is obtained at the Fermi level, where the host semiconductor is doped by at least two types of magnetic atoms of equal concentration. Furthermore, the physical behavior of magnetic system is deeply influenced by the 4f electrons of rare earth element arising from Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, Kondo effect and crystal-field effects, which induces many phenomena such as topological state, heavy-fermion and quantum critical state, magnetic or multipolar ordering. The magnetic ions doped CuInTe2 shows various magnetic properties. Moreover, the previous studies show that the magnetic states of rare earth and TM are strongly related to the external field due to the spin orientation of 3d transition metal and 4f rare earth [16, 17]. In our previous study of Ce doped CuInTe2, the mixture valence state of Ce ions with 4+ and 3+ is confirmed to coexist in CuInxCe1-xTe2 by X-ray Photoelectron Spectroscopy (XPS) and Raman scattering spectrum measurement, Ce ion with 4+ produces one electron and induces the formation of ntype semiconductor[18]. Co doped CuInTe2 semiconductor with chalcopyrite structure shows ferromagnetic characteristics with a Curie temperature around 980 K and p-type semiconductor with a carrier concentration of 2.4 × 1018/cm3 [19]. Based on these previous studies, the designation of CuIn0.9CexCo0.1-xTe2 matches the room temperature dilute magnetic semiconductor, i.e. single phase, diluting magnetic properties by codoping 3d transition metal Co and 4f rare earth Ce into CuInTe2 with 3.33 at % of occupation ratio at In site, room 2
temperature ferromagnetism, and semiconducting characteristics. The codoping effect of Co and Ce on magnetic property and light absorption bandgap in CuIn0.9CexCo0.1-xTe2 is systematically investigated due to the possible exchanging interaction of 3d transition metal Co and 4f rare earth Ce . 2. Material and methods The nominal compositions CuIn0.9CexCo0.1-xTe2 (x =0.02, 0.04, 0.06, 0.08) with purity more than 99.99 wt% for each raw material were prepared using arc melting and vacuum solid state reaction technologies under atmosphere of high pure argon gas. Each sample was remelted for four times for ensuring the homogeneity. The extra Te is prepared for compensation during the melting, furthermore, the tellurium ingredient was added for melting with the precursor Cu-In-Ce-Co alloys to reduce the loss of Te element. The phase structure of CuIn0.9CexCo0.1-xTe2 was measured using Rigaku G/max 2500 Xray diffractometer with Cu Kα1 radiation and power of 8 kW. The field emission scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) were used to investigate the surface morphologies and check the element component of CuIn0.9CexCo0.1-xTe2. The field dependence of magnetization for CuIn0.9CexCo0.1-xTe2 at room temperature was measured by vibrating sample magnetometer (VSM) under the applied fields ranging from 0 to 30 kOe. The thermomagnetic properties were measured by VSM in the temperature range from 300-800K under an applied field of 50Oe. The wavelength dependence of light absorption rate for CuIn0.9CexCo0.1-xTe2 was measured on a Shimadzu 2450 UV-Vis spectrophotometer with scanning range of 300-800nm and scanning step of 0.5nm/s. 3. Result and Discussion The X-ray diffraction analyses show that CuIn0.9CexCo0.1-xTe2 (x=0.02, 0.04, 0.06, 0.08) are single phase with space group of I42d. X-ray diffraction patterns of CuInTe2 and CuIn0.9CexCo0.1-xTe2 are refined by a Rietveld structural refinement technology, as presented in Fig 1. The observed and calculated X-ray diffraction patterns are denoted by red symbols of 3
“+” and green lines, respectively. The vertical blue bars denote the diffraction peak positions, and the lowest lines indicate the differences of diffraction intensities between the observed and calculated XRD patterns. The diffraction peaks of CuIn0.9CexCo0.1-xTe2 can been indexed with a body centered tetragonal structure as listed in appendix. The planar indices are acceptable since both the values of Merit factor M and the Smith factor F are larger than 10. The refined structural parameters of CuIn0.9CexCo0.1-xTe2 are presented in Table 1. The pattern residual factor Rp and the weighted residual pattern factor Rwp are within 10%, which indicate the reliability of the refined results. The lattice parameters are sensitive to the doping contents of Ce and Co，the high ratio of Ce/Co at the In site (4b) causes the lattice expansion and drives Te movement along the a axis. Table 2 lists the bond length and bond angles in CuIn0.9CexCo0.1xTe2,
It shows that the high Ce/Co ratio at In site causes the increase of Cu-Te bond and the
decrease of (In,Co,Ce)-Te bond, and (In,Co,Ce)-Te-(In,Co,Ce) bond-angle also show a regular change with increasing Ce/Co doping ratio. These phenomena are ascribed to the size effect at In site since the order of atomic radius is Ce(1.82 Å), In(1.66 Å) and Co(1.26 Å). SEM morphologies and EDS spectra of CuIn0.9CexCo0.1-xTe2 powers are presented in Fig 2. The grains are apparently in size of micrometer scale with irregular shape. However, the grains tend to be small and disperse uniformly with increasing Ce/Co doping ratio, which illustrates that Ce could refine grain and disperse uniformly. The element components are slightly deviation from the nominal CuIn0.9CexCo0.1-xTe2. The content of Te is slightly lower than the normal composition ones, it implies be due to the volatilization during the melting preparation, and the low Ce/Co doping ratio is ascribed to the incompletion fusion into the basal body. Fig 3 shows that the typical field-dependence of magnetization for CuInTe2, CuIn0.9Co0.1Te2 and CuIn0.9Ce0.02Co0.08Te2 at room temperature under the applied field range of 0-30 kOe. Based on our previous study[19], CuInTe2 shows diamagnetic characteristics with susceptibility around 10-5 due to the diamagnetisms of Cu, In and Te. Co doping into CuInTe2 induces a ferromagnetic transition, and the ferromagnetism can be interpreted by the double exchange mechanism proposed by Zener, the ferromagnetic ordering originates from the itinerate electrons hoping along Co2+-Te-Co3+, one 4p electron of Te is hoping into the vacant 4
eg orbital Co3+(t2g6eg0), and followed by eg electron of Co2+(t2g6eg1) with the same spin direction of 4p electron is hopping into the 4p orbital of Te. Furthermore, the RKKY effect on Ce3+ also contributes to the magnetism of CuIn0.9CexCo0.1-xTe2. Combining the experimental results and above magnetic characters, a mixture magnetism model, which is based on the Ref [17] and [20], is proposed to fit the experimental data, as listed in Eq.1.
( ) 𝑎
(1)
𝑀 = 𝑀𝑠𝐸𝑥𝑝 ― 𝐻 ―𝜒𝐻
Where the first item represents the contribution to magnetization of ferromagnetic phase: MS, H are the saturation magnetization and applied field, respectively; a is coefficient of the applied field and the ratio of a/H shows the tendency of approach to saturation moment. This equation can be regarded as a simplified magnetizing model proposed by Weiss[21] since this equation 𝑎1
𝑎2
𝑎3
can be rewritten by Taylor series expansion algorithm as: M = 𝑀𝑠(1 ― 𝐻1 + 𝐻2 ― 𝐻3⋯). The second item corresponds the contribution of diamagnetism, where χ and H are susceptibility and applied field. The symbol of minus represents the adverse contribution from diamagnetism to the mixture magnetism of CuIn0.9CexCo0.1-xTe2. Fig. 4 shows the fitted field dependence of magnetizations for CuIn0.9CexCo0.1-xTe2 at room temperature, and the fitting parameters are presented in Table 3. The fitted results illustrate the room temperature ferromagnetism of CuIn0.9Ce0.08Co0.02Te2 and CuIn0.9Ce0.06Co0.04Te2, while CuIn0.9CexCo0.1-xTe2 with low Ce/Co doping ratio exhibits mixture characteristics of ferromagnetism and diamagnetism. The saturation magnetization increases with reducing Ce/Co doping ratio due to the substitution of the strong magnetic of Co for Ce. According to the fitting results, the saturation magnetization of CuIn0.9CexCo0.1-xTe2 mainly depends on ferromagnetic characteristics. Comparing to the saturation magnetization of 0.2185 emu/g in CuIn0.9Co0.1Te2 [19], The magnetizations of CuIn0.9Ce0.02Co0.08Te2 and CuIn0.9Ce0.04Co0.06Te2 show significant enhancement by codoping of Ce and Co, which might be ascribed to the exchanging interaction between 4f electron of Ce and 3d electron of Co. The saturation magnetization is closely related to the bond consisting of closest magnetic ions[22], and the closest magnetic bond distance 𝐷𝐶𝑜,𝐶𝑒 ― 𝐶𝑜,𝐶𝑒 depends on the (Ce,Co)-Te bond distance of 𝐷𝐶𝑜,𝐶𝑒 ― 𝑇𝑒 and (Co,Ce)-Te-(Co,Ce) bond angle 𝜃(Co,Ce) ― Te ― (Co,Ce) and follows Eq.2 as below: 5
𝐷𝐶𝑜,𝐶𝑒 ― 𝐶𝑜,𝐶𝑒 = 2𝐷𝐶𝑜,𝐶𝑒 ― 𝑇𝑒sin (𝜃(Co,Ce) ― Te ― (Co,Ce)/2)
(2)
The relationship between the saturation magnetization and the distortion degree can be revealed by the equation as below: M = 𝑀0 + 𝐾𝑚∆𝐷𝐶𝑜,𝐶𝑒 ― 𝐶𝑜,𝐶𝑒
(3)
where M0 is the intrinsic magnetization; ΔDCo,Ce-Co,Ce is the bond length difference, which is defined as ΔDCo,Ce-Co,Ce =|DCo,Ce-Co,Ce(CuIn0.9CexCo0.1-xTe2) –DIn-In(CuInTe2)|; Km is the constant. This model reveals that the correlation between lattice distortion and saturation magnetization by altering the magnetic interaction along (Co,Ce)-(Co,Ce) bond. The ferromagnetic order is enhanced with increasing lattice distortion. The fitted data agree well with the observed ones as shown in Fig 5. The magnetic state of cobalt is variation and shows low spin state at low temperature and high spin state at high temperature, thus, Co spin state is unstable due to its spin rotation driven by increasing temperature[19]. Owing to the room temperature ferromagnetism of CuIn0.9CexCo0.1-xTe2, the field cooling (FC) thermomagnetic curve is measured in temperature range from 300K to 800K for demining their Curie temperatures, as presented in Fig 6. It shows that CuIn0.9CexCo0.1-xTe2 exhibits significant difference for the temperature dependence of magnetization. The magnetizations of CuIn0.9CexCo0.1-xTe2 increase significantly and magnetic transformation temperature tends to be more prominent with increasing Co/Ce doping ratio. For CuIn0.9Ce0.02Co0.08Te2, a magnetic transformation from antiferromagnetic to ferromagnetic is observed at 312K, and the Curie temperature is around 783K. However, a drop is observed around 446K, which might be due to the spin-reorientation as observed in Nd2Fe14C and Ce(Co, Ga)13 and abnormal change of anisotropic parameter k1 [23]. For CuIn0.9Ce0.02Co0.08Te2, the transition originates from the spin rotation at Co sublattice with increasing temperature, since 4f spin rotation of Ce induces magnetostriction due to a non-symmetric crossing configuration in 4f orbital. The exchanging interaction between the Ce- and Co-sublattice can be interpreted with the R 4f band polarization (R= rare earth), which can be described by the 4f-3d (R- T) interaction. The UV-Vis absorption spectra of CuIn0.9CexCo0.1-xTe2 powders are shown in Fig. 4. As the absorbance Ab is determined by the following equation[18]： 6
𝐴𝑏 = 𝛼𝑐𝑙
(4)
where α, c and l are absorption coefficient, concentration of absorption material, and thickness of the liquid layer, respectively. c and l can be determined experimentally and the absorbance Ab is proportion to the absorption coefficient α. Therefore, the value of absorption coefficient α can be determined based on the absorption data. The band gap Eg of light absorption is obtained based on Eq. 5 [24]: 𝛼ℎ𝜈 = 𝐴(ℎ𝜈 ― 𝐸𝑔)𝑛
(5)
where α and ν are the absorption coefficient and photon frequency respectively; A and n are constants. A depends on temperature and photon energy, and the values of the exponent n, in this case, should be 1/2 due to the direct transition of CICCT compounds. Combined with Eq. 4, the equation to determine the optical energy band gap Eg can be written as (𝐴𝑏ℎ𝜈)2 = 𝐴2𝑐2𝑙2(ℎ𝜈 ― 𝐸𝑔)
(6)
A plot of (Abhν)2 versus hν is expected to be a straight line whose intercept on the X axis gives the optical band gap Eg value for CICCT is determined by extrapolating the linear portion of the curve to the X axis, the cross point in the X axis corresponds to Eg value. The light absorption bandgaps of CICCT are in the range of 0.92eV-1.08eV, as shown in Fig.7, the bandgap is slightly broader than that of CuInTe2 (0.91eV-1.0eV). However, According to previous reports, the bandgap of CuIn0.9Ce0.1Te2 is 1.28 eV[18]. It illustrates that the bandgap can be adjusted by codoping of magnetic Co and Ce due to spin-controlled transport mechanism.
4. Conclusions The dilute magnetic semiconductor CuIn0.9CexCo0.1-xTe2 are prepared by arc melting and vacuum solid-state reaction technologies. CuIn0.9CexCo0.1-xTe2 crystallizes into body centered 7
tetragonal structure with a space group of I42d. The codoping of Co and Ce induces the room temperature ferromagnetism in CuIn0.9CexCo0.1-xTe2. The magnetization is increasing with codoping Ce and Co into CuInTe2 due to the exchanging interaction between 4f electron of Ce and 3d electron of Co, which illustrates that both of Co and Ce contributes to the magnetic properties. Magnetic measurements show that Co has the dominating influence on the saturation magnetic moment of CuIn0.9CexCo0.1-xTe2. The high doping ratio of Co and Ce is beneficial for increasing saturation magnetization and the magnetic transformation temperature. (Ce, Co) codoping into CuInTe2 can change the light absorption bandgap from 0.92eV to 1.08eV in CuIn0.9CexCo0.1-xTe2, which is slightly higher than that of CuInTe2. It shows that the light absorption bandgap can be refined by controlling Co/Ce ratio for the potential application of solar cell material.
Acknowledgments This work was supported by the National Key R&D Program of China (2018YFB0905600), the Fundamental Research Funds for the Central Universities of China (2019QN085)
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Figure captions Figure 1. The refined and observed XRD patterns of CuIn0.9CexCo0.1-xTe2 dilute magnetic semiconductors. Figure 2. SEM morphologies and EDS patterns of CuIn0.9CexCo0.1-xTe2 powders, where x=0.02 in 2 a), x=0.04 in 2 b), x=0.06 in 2c), and x=0.08 in 2d) Figure 3. The field dependence of magnetization for CuInTe2, CuIn0.9Co0.1Te2 and CuIn0.9Ce0.02Co0.08Te2 Figure 4. The fitted M-H curves of CuIn0.9CexCo0.1-xTe2 dilute magnetic semiconductor. Figure 5. The fitted magnetic moments of CuIn0.9CexCo0.1-xTe2 at room temperature. Figure 6. The temperature dependence of magnetization for CuIn0.9Ce0.02Co0.08Te2 and CuIn0.9Ce0.08Co0.02Te2 with field cooling mode. Figure 7. UV-Vis absorption spectra of CuIn0.9CexCo0.1-xTe2 dilute magnetic semiconductor
12
Table 1. Rietveld refined structural parameters of CuIn0.9CexCo1-xTe2 Paramete rs a(Å) c(Å) V(Å3) Cu(4a) In(4b) Ce(4b) Co(4b) Te Rwp Rp
CuIn0.9Ce0.02Co0.0 8Te2 6.193(6) 12.411(6) 476.1174 (0,0,0) (0,0,1/2) (0,0,1/2) (0,0,1/2) (0.22032,1/4,1/8) 7.824% 5.862%
CuIn0.9Ce0.04Co0.0 6Te2 6.194(2) 12.414(5) 476.3209 (0,0,0) (0,0,1/2) (0,0,1/2) (0,0,1/2) (0.22057,1/4,1/8) 8.636% 6.226%
13
CuIn0.9Ce0.06Co0.0 4Te2 6.195(1) 12.415(1) 476.4824 (0,0,0) (0,0,1/2) (0,0,1/2) (0,0,1/2) (0.22127,1/4,1/8) 9.770% 7.243%
CuIn0.9Ce0.08Co0.0 2Te2 6.195(5) 12.416(9) 476.6130 (0,0,0) (0,0,1/2) (0,0,1/2) (0,0,1/2) (0.22213,1/4,1/8) 9.809% 6.830%
Table 2. The bond length and bond angle of CuIn0.9CexCo0.1-xTe2 CuInTe2 Band length(Å)
Bond angles(°)
CuIn0.9CexCo00.1 -xTe2
Cu-Te
In-Te
In-Te-In
Cu-TeCu
Cu-TeIn
Te-InTe
Te-CuTe
x=0.02
2.5818
2.7935
103.064
116.193
109.209
107.963
111.166
109.046
112.531
106.074
116.137
109.217
107.978
111.155
115.971
109.047 109.229
112.500 108.012
106.154 111.113
115.771
109.067 109.246
112.432 108.056
106.236 111.064
109.084
112.341
106.330
x=0.04
x=0.06
x=0.08
2.5832
2.5858
2.5886
2.7932
2.7908
2.7875
103.417
103.554
103.726
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Table 3. The fitted magnetizing parameters of CuIn0.9CexCo0.1-xTe2
R2 Value Ms(emu/g ) a(KOe) χ(emu/g• KOe) Standard Error of Ms(emu/g ) Standard Error of μ/KBT(K Oe) Standard Error of χ(emu/g• KOe)
CuIn0.9Ce0.02Co0. 08Te2
CuIn0.9Ce0.04Co0. 06Te2
CuIn0.9Ce0.06Co0. 04Te2
CuIn0.9Ce0.08Co0. 02Te2
0.99239 0.5776
0.98861 0.36391
0.97973 0.20217
0.98021 0.15001
1.6300 0.0025
1.92478 0.00227
1.5113 8.80487E-4
1.92919 8.858E-4
0.00205
0.00172
0.00107
9.2619E-4
0.01323
0.01858
0.01928
0.02424
7.88541E-5
6.40861E-5
4.1911E-5
3.43853E-5
15
Appendix A Table A1. The planar indices of CuIn0.9Ce0.02Co0.08Te2 H
K
L
sin2θobs
sin2θcalc
1 1 2 0.046588 0.046503 1 0 3 0.050335 0.050297 2 0 0 0.062065 0.062098 2 1 1 0.081686 0.081486 2 1 3 0.112532 0.112395 2 2 0 0.124255 0.124196 3 0 1 0.143754 0.143584 3 1 2 0.170786 0.170699 2 2 4 0.186155 0.186013 3 2 1 0.205619 0.205682 3 2 3 0.236506 0.236591 4 0 0 0.24834 0.248392 4 1 1 0.267721 0.26778 3 1 6 0.294253 0.294334 3 2 5 0.298314 0.298408 4 2 4 0.372191 0.372307 5 0 1 0.39199 0.391976 M(17)=20 F(17)=11 a=6.182(1)Å c=12.392(3)Å V=473.62Å3
16
2θobs
2θcalc
24.93 25.93 28.852 33.214 39.201 41.28 44.562 48.82 51.12 53.931 58.198 59.78 62.318 65.701 66.211 75.19 77.525
24.907 25.92 28.86 33.172 39.176 41.27 44.534 48.807 51.099 53.94 58.209 59.787 62.326 65.712 66.223 75.204 77.523
Table A2. The planar indices of CuIn0.9Ce0.04Co0.06Te2 H
K
L
sin2θobs
sin2θcalc
2θobs
2θcalc
1 1 2 2 2 2 3 3 2 3 3 4 4 3 3 4 5
1 0 0 1 1 2 0 1 2 2 2 0 1 1 2 2 0
2 3 0 1 3 0 1 2 4 1 3 0 1 6 5 4 1
0.046523 0.050327 0.062061 0.081547 0.112278 0.12413 0.143627 0.170676 0.186093 0.205522 0.236476 0.248308 0.267649 0.294211 0.298272 0.372132 0.391863
0.046491 0.050287 0.062076 0.081458 0.112363 0.124152 0.143534 0.170643 0.185962 0.20561 0.236515 0.248304 0.267686 0.294263 0.298325 0.37219 0.391838
24.912 25.928 28.851 33.185 39.155 41.259 44.541 48.803 51.111 53.917 58.194 59.776 62.309 65.696 66.206 75.183 77.51
24.903 25.917 28.855 33.167 39.17 41.262 44.526 48.798 51.092 53.93 58.199 59.775 62.314 65.703 66.212 75.19 77.507
M(17)=34 F(17)=18 a=6.183(2)Å c=12.393(1)Å
V=473.82Å3
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Table A3. The planar indices of CuIn0.9Ce0.06Co0.04Te2 H
K
L
SST-OBS
SST-CALC
2TH-OBS
2TH-CALC
1 1 2 2 2 2 3 3 2 3 3 4 2 3 3 4 5
1 0 0 1 1 0 0 1 2 2 2 0 1 1 2 2 0
2 3 0 1 3 4 1 2 4 1 3 0 7 6 5 4 1
0.046479 0.050294 0.062037 0.08142 0.112317 0.123813 0.143401 0.170365 0.18578 0.205257 0.236297 0.247731 0.266932 0.29417 0.298188 0.372014 0.391481
0.046471 0.050292 0.062022 0.081392 0.112313 -0.123864 -0.143414 -0.170515 -0.185886 -0.205436 -0.236357 -0.248087 0.266919 -0.294199 -0.298199 0.371951 -0.391501
24.9 25.919 28.845 33.159 39.162 41.204 44.504 48.756 51.065 53.879 58.17 59.699 62.216 65.691 66.195 75.169 77.465
24.898 25.919 28.842 33.153 39.161 41.212 44.506 48.779 51.08 53.905 58.178 59.747 62.215 65.695 66.196 75.161 77.467
M(17)=27 F(17)=17 a=6.185(9)Å c=12.389(8)Å
V=474.11Å3
18
Table A4. The planar indices of CuIn0.9Ce0.08Co0.02Te2 H
K
L
sin2θobs
sin2θcalc
2θobs
2θcalc
1 1 2 2 2 2 3 3 2 3 3 4 4 3 3 2 5
1 0 0 1 1 2 0 1 2 2 2 0 1 1 2 2 0
2 3 0 1 3 0 1 2 4 1 3 0 1 6 5 8 1
0.046492 0.050377 0.062097 0.081529 0.112307 0.123915 0.1435 0.170402 0.185697 0.205281 0.236088 0.247891 0.267111 0.293756 0.297892 0.371132 0.390909
0.04643 0.050243 0.061972 0.081326 0.112215 -0.123944 0.143298 0.170374 -0.185722 0.20527 -0.236159 0.247888 -0.267242 -0.293931 -0.297937 0.371056 -0.391185
24.904 25.941 28.86 33.181 39.16 41.221 44.52 48.761 51.053 53.883 58.141 59.721 62.239 65.639 66.158 75.064 77.398
24.887 25.906 28.83 33.139 39.143 41.226 44.487 48.757 51.056 53.881 58.151 59.72 62.256 65.661 66.164 75.055 77.43
M(17)=18 F(17)=10 a=6.188(4)Å c=12.396(3)Å
V=474.74Å3
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We have read and have abided by the statement of ethical standards for manuscripts submitted to Journal of Magnetism and Magnetic Materials. We declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper (MAGMA_2019_3094_R1).
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Declaration of interests
☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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Highlights
1. Ferromagnetism with slight diamagnetism character at room temperature for CuIn0.9CexCo0.1-xTe2 2. Enhancement on magnetism with electron interaction of Ce4f and Co3d when compared to Cu(In, Co)Te2 3. Higher Co/Ce doping ratio leads to a greater magnetism and more prominent magnetic transformation 4. Adjusting light absorption bandgap slightly higher than CuInTe2.
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