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Magnetic moment and susceptibility measurement studies of double rare earth hydrogen selenite crystals
Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
Magnetic moment and susceptibility measurement studies of double rare earth hydrogen selenite crystals P.P. Pradyumnan *, Cyriac Joseph, M.A. Ittyachen Department of Physics, University of Calicut, Kerala 673 635, India Crystal Physics Division, School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686 560, India Received 17 September 1998; received in revised form 25 November 1998
Abstract Doubly mixed and single crystals of rare earth hydrogen selenite (REHS) crystals are grown and characterized. The variation of magnetic moment of these crystals with di!erent external magnetic "elds have been thoroughly studied in di!erent stoichiometric combination of the constituent rare earths. Magnetic susceptibility and e!ective magnetic moment of the crystals are in well tallied with the theoretically calculated results. 1999 Elsevier Science B.V. All rights reserved. Keywords: Magnetic moment; Susceptibility; VSM; Rare earths; Mixed crystals
1. Introduction The rare earth compounds are well established because of its outstanding and technologically exploited magnetic properties. A great deal of work has been reported in the study of magnetic property of rare earth elements [1}3]. A great number of rare earth compound crystal has been grown by using various growth techniques [4}7]. Recently the growth and magnetic properties of some rare earth oxalate crystals have been reported [8]. In this work the authors report the growth, magnetic moment and magnetic susceptibility measurements of single and double rare earth hydrogen selenite (REHS) crystals in di!erent stoichiometries. The
* Corresponding author. E-mail: [email protected].
grown crystals are praseodymium hydrogen selenite (PHS), neodymium hydrogen selenite (NHS), samarium hydrogen selenite (SHS), praseodymium neodymium hydrogen selenite (PNHS), praseodymium samarium hydrogen selenite (PSHS), neodymium samarium hydrogen selenite (NSHS). The doubly mixed crystals are grown in di!erent stoichiometric ratio also. All these crystals are grown by the gel di!usion techniques. The grown crystals are characterized by using various conventional techniques.
2. Experimental studies The PHS, NHS, SHS, PNHS, PSHS and NSHS crystals were grown by the single di!usion technique. AR grade sodium metasilicate (SMS) having
0304-8853/99/$ } see front matter 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 - 8 8 5 3 ( 9 8 ) 0 1 0 7 8 - 6
P.P. Pradyumnan et al. / Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
a density of 1.025 g/cm mixed with 0.5 M selenous acid to get a desired pH (6.5) was allowed to set in test-tubes having 25 mm diameter and 150 mm in length. Aqueous solution of single and doubly mixed rare earth nitrates (IRE, Cochin) are poured gently over the set gel. The outer electrolytes slowly di!use into the gel and the controlled reaction resulted in the formation of hydrogen selenite crystals of constituent rare earths having a layered nature. The magnetic property of the crystals were studied by using a vibrating sample magnetometer (VSM) by applying di!erent magnetic "elds. The susceptibilities of the crystals are calculated from the measured magnetic moment.
493
3. Results and discussion
is observed that the percentage of incorporation of di!erent rare earth ions in the doubly mixed crystals are proportional to the stoichiometric ratio of the interacting ions in the upper electrolyte. The TG-DTA studies of the crystals agree with the proposed formula. The magnetic moment of the grown crystals were determined for di!erent external "elds and the gram susceptibility was calculated. The summary is given in Tables 1}4. The variation of the e!ective magnetic moment for the di!erent stoichiometric ratio of the doubly mixed rare earth crystals have been depicted in Figs. 1}3. The magnetic moment of the mixed crystals re#ect the magnetic moment of the major constituent rare earth ions. The molar susceptibility of the crystals were calculated by the equation
The presence of the rare earth ions in the grown crystals are veri"ed by optical absorption studies. It
sM s " ,
n
(1)
Table 1 The Magnetic data of single selenite crystals Field (¹)
0.2 0.4 0.6 0.8 1.0
Crystal (PHS)
Crystal (NHS)
Crystal (SHS)
Moment (; 10\ JT\)
s (JT\ kg\)
Moment (; 10\ JT\)
s (JT\ kg\)
Moment (; 10\ JT\)
s (JT\ kg\)
0.090 0.166 0.262 0.359 0.443
0.1219 0.1124 0.1183 0.1216 0.1200
0.080 0.125 0.204 0.285 0.345
0.1580 0.1235 0.1343 0.1408 0.1363
0.020 0.036 0.054 0.081 0.101
0.01316 0.01184 0.01184 0.01332 0.01320
Table 2 Magnetic data of praseodymium neodymium hydrogen selenite crystals Field (¹)
0.2 0.4 0.6 0.8 1.0
PNHS (P"25% N"75%)
PNHS (P"50% N"50%)
PNHS (P"75% N"25%)
Moment (; 10\ JT\)
s (JT\kg\)
Moment (; 10\ JT\)
s (JT\ kg\)
Moment (;10\ JT\)
s (JT\kg\)
0.084 0.154 0.216 0.312 0.410
0.1312 0.1203 0.1125 0.1218 0.1281
0.105 0.163 0.251 0.333 0.408
0.1416 0.1350 0.1394 0.1387 0.1360
0.088 0.146 0.237 0.316 0.401
0.1491 0.1237 0.1339 0.1338 0.1359
494
P.P. Pradyumnan et al. / Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
Table 3 Magnetic data of praseodymium samarium hydrogen selenite crystals Field (¹)
0.2 0.4 0.6 0.8 1.0
PSHS (P"25% S"75%)
PSHS (P"50% S"50%)
PSHS (P"75% S"25%)
Moment (;10\ JT\)
s (JT\ kg\)
Moment (; 10\ JT\)
s (JT\ kg\)
Moment (;10\ JT\)
s (JT\ kg\)
0.040 0.088 0.140 0.190 0.232
0.03322 0.03650 0.03875 0.03945 0.03853
0.042 0.076 0.110 0.160 0.175
0.06154 0.05846 0.05641 0.06154 0.05661
0.058 0.097 0.158 0.214 0.262
0.08380 0.07001 0.07611 0.07730 0.07572
Table 4 Magnetic data of neodymium samarium hydrogen selenite crystals Field (¹)
0.2 0.4 0.6 0.8 1.0
NSHS (N"25% S"75%)
NSHS (N"50% S"50%)
NSHS (N"75% S"25%)
Moment (;10\ JT\)
s (JT\ kg\)
Moment (;10\ JT\)
s (JT\ kg\)
Moment (;10\ JT\)
s (JT\ kg\)
0.025 0.041 0.070 0.102 0.125
0.03307 0.02712 0.03086 0.03306 0.03156
0.045 0.083 0.142 0.190 0.227
0.06132 0.05650 0.06450 0.06470 0.06181
0.062 0.106 0.183 0.250 0.302
0.09281 0.07931 0.09130 0.09350 0.90402
where M is the molecular weight of the sample, &n' is the number of rare earth ions per molecule, s is the gram susceptibility, s is the molar susceptibility
[8]. The e!ective magnetic moment of the crystals were calculated using the equation k "0.8942[(s ) ¹] .
(2)
The molar susceptibility values were corrected (s ) for diamagnetism [9], ¹ is the temperature
in absolute units. The theoretical values of the e!ective moment of a tripositive rare earth ion is given by the relation k "g[J(J#1)]
(3)
and the average value for the rare earth ions incorporated in the crystals are calculated. Table 5 shows the corrected values of the molar susceptibil-
ity and the experimental and theoretical values of the e!ective magnetic moments of the doubled hydrogen selenite crystals. Figs. 1}3 shows the stoichiometric variation in e!ective magnetic moment of the mixed crystals. The observed and calculated e!ective magnetic moments of the doubly mixed rare earth hydrogen selenite crystals are well matched with each other. It reveals that the diamagnetic nature of the free rare earth ion bound to the hydrogen selenite part of the crystal makes only negligible contribution to the actual magnetic moment of the PNHS, PSHS, NSHS crystals. It is found that in all the above doubly mixed hydrogen selenite crystals, the rare earth ions have only slight di!erence in electronic con"guration as in pure metals and its magnetic properties are also a!ected negligibly by the HSeO , SeO bonding Tables 6 and 7.
P.P. Pradyumnan et al. / Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
Fig. 1. The variation of Bohr magneton with the percentage of Pr> in praseodymium neodymium hydrogen selenite crystal.
495
Fig. 3. The variation of Bohr magneton with the percentage of Nd> in praseodymium samarium hydrogen selenite crystal.
Table 5 Molar susceptibility and e!ective magnetic moments of the PNHS crystals % of P and N
P
N
0 25 50 75 100
100 75 50 25 0
Corrected E!ective magnetic moment molar sus- (Bohr magneton) ceptibility (JT\ mol\)
0.06188 0.05325 0.05944 0.05843 0.05124
Experimental
Theoretical
3.799 3.5736 3.7734 3.7437 3.5058
3.62 3.61 3.60 3.59 3.58
4. Conclusions
Fig. 2. The variation of Bohr magneton with the percentage of Pr> in praseodymium samarium hydrogen selenite crystal.
Single and doubly mixed rare earth hydrogen selenite crystals are obtained by the controlled di!usion of the reactant through the gel medium and is characterized by di!erent techniques. The
496
P.P. Pradyumnan et al. / Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
Table 6 Molar susceptibility and e!ective magnetic moments of the PSHS crystals % of P and S
P
S
0 25 50 75 100
100 75 50 25 0
Corrected E!ective magnetic moment molar sus- (Bohr magneton) ceptibility (JT\ mol\)
0.00508 0.01628 0.06018 0.03325 0.05124
Experimental
Theoretical
1.1495 1.9760 2.5102 2.8068 3.5058
0.85 1.5325 2.215 2.8975 3.58
Table 7 Molar susceptibility and e!ective magnetic moments of the NSHS crystals % of N and S
N
S
0 25 50 75 100
100 75 50 25 0
Corrected E!ective magnetic moment molar sus- (Bohr magneton) ceptibility (JT\ mol\)
0.00508 0.01388 0.02698 0.03818 0.06188
Experimental
Theoretical
1.1495 1.8193 2.5439 3.0554 3.799
0.85 1.5425 2.235 2.92 3.62
magnetic susceptibility and e!ective magnetic moment of the stoichiometrically di!erent doubly mixed crystals were calculated by recording the
variation of the magnetic moment with external "eld. E!ective magnetic moment observed and theoretically calculated are well tallied. This suggests that the rare earth ions are weakly perturbed by the crystalline lattice and that the atomic properties of the rare earth ions are retained in the mixed states.
Acknowledgements The authors are thankful to DST, Govt. of India for providing "nancial assistance and RSIC, I.I.T. Madras for analytical facilities. One of the author P.P. Pradyumnan. is thankful to Prof. K. Neelakandan, Head, Department of Physics, University of Calicut for providing facilities in the department.
References [1] [2] [3] [4] [5] [6] [7] [8] [9]
D.K. Derb Ray, E. Ryba, J. Appl. Phys. 38 (1967) 3459. G. Busch, Appl. Phys. 3 (1967) 1386. N. Nerson, J. Appl. Phys. 44 (1973) 4727. C. Joseph, G. Varghese, M.A. Ittyachen, Cryst. Res. Technol. 30 (1995) 159. Jayakumari Issac, M.A. Ittyachen, K. Abdulkhader, Cryst. Res. Technol. 7 (1992) K872. G. Varghese, M.A. Ittyachen, J. Issac, Cryst. Res. Technol. 25 (1990) K153. A. Castro, R. Enjalbert, M. de Pedro, J.C. Trombe, J. Solid State Chem. 112 (1994) 418. Cyriac Joseph, George Varghese, M.A. Ittyachen, Cryst. Res. Technol. 31 (1996) 127. P.W. Selwood, Magnetochemistry, Interscience, New York. 1956.
Magnetic moment and susceptibility measurement studies of double rare earth hydrogen selenite crystals P.P. Pradyumnan *, Cyriac Joseph, M.A. Ittyachen Department of Physics, University of Calicut, Kerala 673 635, India Crystal Physics Division, School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686 560, India Received 17 September 1998; received in revised form 25 November 1998
Abstract Doubly mixed and single crystals of rare earth hydrogen selenite (REHS) crystals are grown and characterized. The variation of magnetic moment of these crystals with di!erent external magnetic "elds have been thoroughly studied in di!erent stoichiometric combination of the constituent rare earths. Magnetic susceptibility and e!ective magnetic moment of the crystals are in well tallied with the theoretically calculated results. 1999 Elsevier Science B.V. All rights reserved. Keywords: Magnetic moment; Susceptibility; VSM; Rare earths; Mixed crystals
1. Introduction The rare earth compounds are well established because of its outstanding and technologically exploited magnetic properties. A great deal of work has been reported in the study of magnetic property of rare earth elements [1}3]. A great number of rare earth compound crystal has been grown by using various growth techniques [4}7]. Recently the growth and magnetic properties of some rare earth oxalate crystals have been reported [8]. In this work the authors report the growth, magnetic moment and magnetic susceptibility measurements of single and double rare earth hydrogen selenite (REHS) crystals in di!erent stoichiometries. The
* Corresponding author. E-mail: [email protected].
grown crystals are praseodymium hydrogen selenite (PHS), neodymium hydrogen selenite (NHS), samarium hydrogen selenite (SHS), praseodymium neodymium hydrogen selenite (PNHS), praseodymium samarium hydrogen selenite (PSHS), neodymium samarium hydrogen selenite (NSHS). The doubly mixed crystals are grown in di!erent stoichiometric ratio also. All these crystals are grown by the gel di!usion techniques. The grown crystals are characterized by using various conventional techniques.
2. Experimental studies The PHS, NHS, SHS, PNHS, PSHS and NSHS crystals were grown by the single di!usion technique. AR grade sodium metasilicate (SMS) having
0304-8853/99/$ } see front matter 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 - 8 8 5 3 ( 9 8 ) 0 1 0 7 8 - 6
P.P. Pradyumnan et al. / Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
a density of 1.025 g/cm mixed with 0.5 M selenous acid to get a desired pH (6.5) was allowed to set in test-tubes having 25 mm diameter and 150 mm in length. Aqueous solution of single and doubly mixed rare earth nitrates (IRE, Cochin) are poured gently over the set gel. The outer electrolytes slowly di!use into the gel and the controlled reaction resulted in the formation of hydrogen selenite crystals of constituent rare earths having a layered nature. The magnetic property of the crystals were studied by using a vibrating sample magnetometer (VSM) by applying di!erent magnetic "elds. The susceptibilities of the crystals are calculated from the measured magnetic moment.
493
3. Results and discussion
is observed that the percentage of incorporation of di!erent rare earth ions in the doubly mixed crystals are proportional to the stoichiometric ratio of the interacting ions in the upper electrolyte. The TG-DTA studies of the crystals agree with the proposed formula. The magnetic moment of the grown crystals were determined for di!erent external "elds and the gram susceptibility was calculated. The summary is given in Tables 1}4. The variation of the e!ective magnetic moment for the di!erent stoichiometric ratio of the doubly mixed rare earth crystals have been depicted in Figs. 1}3. The magnetic moment of the mixed crystals re#ect the magnetic moment of the major constituent rare earth ions. The molar susceptibility of the crystals were calculated by the equation
The presence of the rare earth ions in the grown crystals are veri"ed by optical absorption studies. It
sM s " ,
n
(1)
Table 1 The Magnetic data of single selenite crystals Field (¹)
0.2 0.4 0.6 0.8 1.0
Crystal (PHS)
Crystal (NHS)
Crystal (SHS)
Moment (; 10\ JT\)
s (JT\ kg\)
Moment (; 10\ JT\)
s (JT\ kg\)
Moment (; 10\ JT\)
s (JT\ kg\)
0.090 0.166 0.262 0.359 0.443
0.1219 0.1124 0.1183 0.1216 0.1200
0.080 0.125 0.204 0.285 0.345
0.1580 0.1235 0.1343 0.1408 0.1363
0.020 0.036 0.054 0.081 0.101
0.01316 0.01184 0.01184 0.01332 0.01320
Table 2 Magnetic data of praseodymium neodymium hydrogen selenite crystals Field (¹)
0.2 0.4 0.6 0.8 1.0
PNHS (P"25% N"75%)
PNHS (P"50% N"50%)
PNHS (P"75% N"25%)
Moment (; 10\ JT\)
s (JT\kg\)
Moment (; 10\ JT\)
s (JT\ kg\)
Moment (;10\ JT\)
s (JT\kg\)
0.084 0.154 0.216 0.312 0.410
0.1312 0.1203 0.1125 0.1218 0.1281
0.105 0.163 0.251 0.333 0.408
0.1416 0.1350 0.1394 0.1387 0.1360
0.088 0.146 0.237 0.316 0.401
0.1491 0.1237 0.1339 0.1338 0.1359
494
P.P. Pradyumnan et al. / Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
Table 3 Magnetic data of praseodymium samarium hydrogen selenite crystals Field (¹)
0.2 0.4 0.6 0.8 1.0
PSHS (P"25% S"75%)
PSHS (P"50% S"50%)
PSHS (P"75% S"25%)
Moment (;10\ JT\)
s (JT\ kg\)
Moment (; 10\ JT\)
s (JT\ kg\)
Moment (;10\ JT\)
s (JT\ kg\)
0.040 0.088 0.140 0.190 0.232
0.03322 0.03650 0.03875 0.03945 0.03853
0.042 0.076 0.110 0.160 0.175
0.06154 0.05846 0.05641 0.06154 0.05661
0.058 0.097 0.158 0.214 0.262
0.08380 0.07001 0.07611 0.07730 0.07572
Table 4 Magnetic data of neodymium samarium hydrogen selenite crystals Field (¹)
0.2 0.4 0.6 0.8 1.0
NSHS (N"25% S"75%)
NSHS (N"50% S"50%)
NSHS (N"75% S"25%)
Moment (;10\ JT\)
s (JT\ kg\)
Moment (;10\ JT\)
s (JT\ kg\)
Moment (;10\ JT\)
s (JT\ kg\)
0.025 0.041 0.070 0.102 0.125
0.03307 0.02712 0.03086 0.03306 0.03156
0.045 0.083 0.142 0.190 0.227
0.06132 0.05650 0.06450 0.06470 0.06181
0.062 0.106 0.183 0.250 0.302
0.09281 0.07931 0.09130 0.09350 0.90402
where M is the molecular weight of the sample, &n' is the number of rare earth ions per molecule, s is the gram susceptibility, s is the molar susceptibility
[8]. The e!ective magnetic moment of the crystals were calculated using the equation k "0.8942[(s ) ¹] .
(2)
The molar susceptibility values were corrected (s ) for diamagnetism [9], ¹ is the temperature
in absolute units. The theoretical values of the e!ective moment of a tripositive rare earth ion is given by the relation k "g[J(J#1)]
(3)
and the average value for the rare earth ions incorporated in the crystals are calculated. Table 5 shows the corrected values of the molar susceptibil-
ity and the experimental and theoretical values of the e!ective magnetic moments of the doubled hydrogen selenite crystals. Figs. 1}3 shows the stoichiometric variation in e!ective magnetic moment of the mixed crystals. The observed and calculated e!ective magnetic moments of the doubly mixed rare earth hydrogen selenite crystals are well matched with each other. It reveals that the diamagnetic nature of the free rare earth ion bound to the hydrogen selenite part of the crystal makes only negligible contribution to the actual magnetic moment of the PNHS, PSHS, NSHS crystals. It is found that in all the above doubly mixed hydrogen selenite crystals, the rare earth ions have only slight di!erence in electronic con"guration as in pure metals and its magnetic properties are also a!ected negligibly by the HSeO , SeO bonding Tables 6 and 7.
P.P. Pradyumnan et al. / Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
Fig. 1. The variation of Bohr magneton with the percentage of Pr> in praseodymium neodymium hydrogen selenite crystal.
495
Fig. 3. The variation of Bohr magneton with the percentage of Nd> in praseodymium samarium hydrogen selenite crystal.
Table 5 Molar susceptibility and e!ective magnetic moments of the PNHS crystals % of P and N
P
N
0 25 50 75 100
100 75 50 25 0
Corrected E!ective magnetic moment molar sus- (Bohr magneton) ceptibility (JT\ mol\)
0.06188 0.05325 0.05944 0.05843 0.05124
Experimental
Theoretical
3.799 3.5736 3.7734 3.7437 3.5058
3.62 3.61 3.60 3.59 3.58
4. Conclusions
Fig. 2. The variation of Bohr magneton with the percentage of Pr> in praseodymium samarium hydrogen selenite crystal.
Single and doubly mixed rare earth hydrogen selenite crystals are obtained by the controlled di!usion of the reactant through the gel medium and is characterized by di!erent techniques. The
496
P.P. Pradyumnan et al. / Journal of Magnetism and Magnetic Materials 202 (1999) 492}496
Table 6 Molar susceptibility and e!ective magnetic moments of the PSHS crystals % of P and S
P
S
0 25 50 75 100
100 75 50 25 0
Corrected E!ective magnetic moment molar sus- (Bohr magneton) ceptibility (JT\ mol\)
0.00508 0.01628 0.06018 0.03325 0.05124
Experimental
Theoretical
1.1495 1.9760 2.5102 2.8068 3.5058
0.85 1.5325 2.215 2.8975 3.58
Table 7 Molar susceptibility and e!ective magnetic moments of the NSHS crystals % of N and S
N
S
0 25 50 75 100
100 75 50 25 0
Corrected E!ective magnetic moment molar sus- (Bohr magneton) ceptibility (JT\ mol\)
0.00508 0.01388 0.02698 0.03818 0.06188
Experimental
Theoretical
1.1495 1.8193 2.5439 3.0554 3.799
0.85 1.5425 2.235 2.92 3.62
magnetic susceptibility and e!ective magnetic moment of the stoichiometrically di!erent doubly mixed crystals were calculated by recording the
variation of the magnetic moment with external "eld. E!ective magnetic moment observed and theoretically calculated are well tallied. This suggests that the rare earth ions are weakly perturbed by the crystalline lattice and that the atomic properties of the rare earth ions are retained in the mixed states.
Acknowledgements The authors are thankful to DST, Govt. of India for providing "nancial assistance and RSIC, I.I.T. Madras for analytical facilities. One of the author P.P. Pradyumnan. is thankful to Prof. K. Neelakandan, Head, Department of Physics, University of Calicut for providing facilities in the department.
References [1] [2] [3] [4] [5] [6] [7] [8] [9]
D.K. Derb Ray, E. Ryba, J. Appl. Phys. 38 (1967) 3459. G. Busch, Appl. Phys. 3 (1967) 1386. N. Nerson, J. Appl. Phys. 44 (1973) 4727. C. Joseph, G. Varghese, M.A. Ittyachen, Cryst. Res. Technol. 30 (1995) 159. Jayakumari Issac, M.A. Ittyachen, K. Abdulkhader, Cryst. Res. Technol. 7 (1992) K872. G. Varghese, M.A. Ittyachen, J. Issac, Cryst. Res. Technol. 25 (1990) K153. A. Castro, R. Enjalbert, M. de Pedro, J.C. Trombe, J. Solid State Chem. 112 (1994) 418. Cyriac Joseph, George Varghese, M.A. Ittyachen, Cryst. Res. Technol. 31 (1996) 127. P.W. Selwood, Magnetochemistry, Interscience, New York. 1956.