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Temperature dependence of GdVO4:Eu3+ luminescence
Journal of Alloys and Compounds 333 (2002) 215–218
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Temperature dependence of GdVO 4 :Eu 31 luminescence a,b
Bo Liu , Chaoshu Shi a
a,b,c ,
*, Qingli Zhang c , Yonghu Chen b
Structure Research Laboratory, University of Science and Technology of China, Hefei, 230026, China b NSRL, University of Science and Technology of China, Hefei, 230029, China c Department of Physics, University of Science and Technology of China, Hefei, 230026, China Received 17 April 2001; accepted 18 June 2001
Abstract The temperature dependence of the GdVO 4 :Eu 31 luminescence from the Eu 31 5 D 0 → 7 F J transition above room temperature has been studied. The intensity of the luminescence when excited at 313 and 365 nm increases rapidly as temperature rises up to 600 K while the emission intensity at 254 nm only changes a little. The origin of this novel phenomenon is analyzed and discussed by energy transfer from host to Eu 31 in terms of a configurational-coordinate model. 2002 Elsevier Science B.V. All rights reserved. Keywords: Rare earth compounds; Optical materials; Luminescence PACS: 78.55.-m; 78.20. Bh; 78.20. Nv
1. Introduction As laser crystals, GdVO 4 :RE 31 (such as Pr 31 , Nd 31 , Ho 31 , Er 31 , Tm 31 , Yb 31 ) have been extensively investigated [1–4]. Although GdVO 4 :Eu 31 will not be used in laser operations, it is a significant red-emitting material with a main emission peak at 619 nm. The luminescence intensity of GdVO 4 :Eu 31 is in the same order as that of YVO 4 :Eu 31 [5]. Recent research has shown that the emission and excitation spectra depend on doping manners and the sintering atmosphere [6], from which we can understand the process of energy transfer. Additionally, Gd–Eu is also a good physical system to study on energy transfer. Recently, our experiments showed that GdVO 4 :Eu 31 has good temperature properties and a higher quenching temperature than YVO 4 :Eu 31 , so it is very suitable for application in high temperature environments such as high-pressure mercury-vapor lamps. The temperature dependence of the 313 and 365 nm excitation was different from the 254 nm excitation. The purpose of this
*Corresponding author. E-mail address: [email protected] (C. Shi).
article is to study the temperature properties of the GdVO 4 :Eu 31 luminescence and to give some possible explanations for its mechanism.
2. Experimental A polycrystalline sample of GdVO 4 :Eu 31 (10 mol%) was made by reacting stoichiometric proportions of V2 O 5 and Gd 2 O 3 of 99.99 and 99.95% purity, respectively. The nitric acid solution of Eu 2 O 3 was used to dope Eu 31 into GdVO 4 . The mixture was sintered in an air atmosphere at 8008C for 8 h, then the polycrystalline GdVO 4 :Eu 31 was obtained. X-Ray diffraction measurements (XRD) were carried out at room temperature using a D/ Mrax-rA Rotation Anode X-ray Diffractometer with Cu Ka radiation. From the XRD, it is concluded that the sample crystallized well and has the ZrSiO 4 structure, belonging to the space group I4 /amd. The temperature dependence of the GdVO 4 :Eu 31 luminescence was obtained under excitation at 313 and 365 nm from a high-pressure mercury-vapor lamp and 254 nm from a low-pressure mercury-vapor lamp, using suitable filters. The transmission of the filter used in a high-
0925-8388 / 02 / $ – see front matter 2002 Elsevier Science B.V. All rights reserved. PII: S0925-8388( 01 )01711-X
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B. Liu et al. / Journal of Alloys and Compounds 333 (2002) 215 – 218
pressure mercury-vapor lamp is in the range 300–400 nm in which there are two strong emission lines at 313 and 365 nm. These experiments include emission spectra at different temperatures and emission peak intensities as a function of temperature with different excitation wavelengths. A TC-100U temperature controller with different programs was used for temperature measurement. The emission spectra were measured with an HRD-1 double grating monochromator made by the J-Y Company, France. The excitation spectrum was measured with a Hitachi 850 type fluorescence spectrometer at room temperature.
3. Experimental results
3.1. Temperature dependence of GdVO4 : Eu 31 luminescence excited at 313 and 365 nm The emission spectra at different temperatures above room temperature are shown in Fig. 1. The characteristic emissions of Eu 31 were observed, including those peaking at 608, 616 and 619 nm for 5 D 0 → 7 F 2 transition, at 594 and 598 nm for 5 D 0 → 7 F 1 transition and at 538 nm for 5 D 1 → 7 F 1 transition. Each increases with rising temperature, and the relative intensity of the emission lines remains constant. Fig. 2 shows the emission intensities at 619, 615, 594 and 698 nm as a function of temperature. In the range of 300–600 K, each emission line increases as the temperature rises, especially above 400 K, and there is a rapid increase without intensity saturation up to 600 K. The emission intensity at 600 K is 20 times stronger than that at 300 K.
Fig. 2. The intensity of different emissions of Eu 31 as a function of temperature excited at 313 and 365 nm.
3.2. Temperature dependence of GdVO4 : Eu 31 luminescence excited at 254 nm The characteristic emission excited at 254 nm is the same as that when excited at 313 and 365 nm. The intensity at 619, 698 and 538 nm emissions as a function of temperature is shown in Fig. 3. It can clearly be seen that the emission intensities at 619 and 698 nm decreased as the temperature rises while the intensity at 538 nm increased with rising temperature. The changes are all modest. This is quite different from the dependences observed under excitation at 313 and 365 nm.
3.3. The excitation spectrum of the 619 -nm emission from GdVO4 : Eu 31 at room temperature As shown in Fig. 4, it can be observed that the excited spectrum of the 619-nm emission contains two main
Fig. 1. Emission spectra of GdVO 4 :Eu at different temperatures excited at 313 and 365 nm.
Fig. 3. The intensity of different emissions of Eu 31 as a function of temperature excited at 254 nm.
B. Liu et al. / Journal of Alloys and Compounds 333 (2002) 215 – 218
217
Fig. 4. Excitation spectrum of GdVO 4 :Eu 31 with emission wavelength 619 nm at RT.
excitation bands peaking at about 250 and 310 nm, besides the intrinsic excitation of Eu 31 . The intensity of intrinsic excitation is much weaker than that of the excitation bands at 250 and 310 nm.
4. Discussion Many compounds doped with europium ions such as YVO 4 :Eu 31 , Gd 2 O 3 :Eu 31 , Y 2 O 3 :Eu 31 , GdPO 4 :Eu 31 , have similar temperature properties of luminescence to GdVO 4 :Eu 31 and a high quenching temperature [7–9]. Similar to YVO 4 :Eu, GdVO 4 :Eu belongs to the ZrSiO 4 structure. The Eu 31 ions enter the host lattices of GdVO 4 or YVO 4 and substitute for Gd 31 or Y 31 . Eu 31 and its surrounding thus form a molecular aggregate of symmetry D2d . So many similar properties exist between GdVO 4 :Eu 31 and YVO 4 :Eu 31 . The excitation spectra for both GdVO 4 :Eu 31 and YVO 4 :Eu 31 consist of two main excitation bands peaking at about 250 and 320 nm [7]. Kano et al. [9] reported that for YVO 4 :Eu 31 , the integrated emission intensity excited at 254 nm changes slightly with increasing temperature while the integrated intensity increases rapidly when excited at 313 and 365 nm in the temperature range 100–450 K. Moskvin et al. [10] also reported that the intensity of YVO 4 :Eu 31 luminescence increased rapidly when excited by a high pressure mercury-vapor lamp and reached a maximum when the temperature reached 500 K. For GdVO 4 :Eu 31 , there is a more significant increase without saturation up to 600 K. GdVO 4 :Eu 31 is a typical host sensitizing luminescence material. So its emission intensity and efficiency mainly depend on the host absorption and energy transfer from the host to activators. Concerning the excitation of the Eu 31 emission, a charge-transfer state (CTS) should be considered. For Eu 31 in eight-coordination, the charge-transfer band is in the region from 220 to 270 nm [11]. The band peaking at 310 nm is due to vanadate absorption followed
Fig. 5. Scheme of GdVO 4 :Eu 31 energy levels and transitions.
by energy transfer to activators Eu 31 . In fact, the intrinsic Eu 31 excitation is much weaker than host excitation. Fig. 5 represents a scheme of GdVO 4 :Eu 31 energy levels and transitions. In order to analyse the different temperature dependences under excitation at 313 and 365 nm and at 254 nm, a configurational-coordination model shown in Fig. 6 was proposed. When GdVO 4 :Eu 31 is
Fig. 6. Configurational-coordinate diagram for Eu 31 in GdVO 4 :Eu 31 .
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excited at 313 nm, the excitation energy can be transferred to Eu 31 through VO 43- , which makes Eu 31 rise to its excited states which are lower than its CTS. For excitation at 365 nm, Eu 31 ions are excited to the states 5 D J directly. The Eu 31 can be fed into 5 D J through cascade relaxation according to the order 5 D 3 , 5 D 2 , 5 D 1 , 5 D 0 accompanied by phonon emissions. The time of relaxation between 5 D J (such as from 5 D 1 to 5 D 0 ) is of the order of 10 24 s. Both 313- and 365-nm excitation cannot excite Eu 31 into its CTS directly. Under the excitation of 365 nm, Eu 31 can be excited into the 365-nm level of Eu 31 shown in Fig. 6 and at the same time, form many vibration states whose energy is higher than that of 356 nm due to the effect of temperature. When the energy of vibration states is close to CTS, it can enter CTS more easily. When the temperature rises, it can be fed into CTS of Eu 31 through thermal disturbance. So when the temperature rises, the probability of going from the vibration state of 365 nm level of Eu 31 to CTS will increase. Subsequently it can relax along the parabola of the configurational-coordinate, shown in Fig. 6. During the process of relaxation, the energy can be transferred to 5 D 0 , 5 D 1 , 5 D 2 , 5 D 3 directly. This period is much less than 10 27 s and needs no cascade relaxation from 5 D 3 to 5 D 2 until 5 D 0 . Therefore if CTS acts as middle state, the process of luminescence will be influenced by temperature intensively and causes the enhancement of luminescent intensity when temperature rises. If Eu 31 can enter CTS, the emission from 5 D 0 to 7 F J will become more efficient because it is not necessary to involve 5 D 2 , 5 D 1 , etc. For the 365-nm excitation, Eu 31 cannot be excited into CTS, but can only come into CTS by making use of thermal disturbance. So the efficiency of 5 D 0 emission is temperature-dependent and when temperature rises the emission of 5 D 0 will increase. In the range of measurement, no decrease in luminescence was observed so the quenching temperature is higher than 600 K, which corresponds to the intersection of two parabolas. When excited at 254 nm, Eu 31 ions are directly excited into CTS, then promptly come into lower excited states such as 5 D 0 , 5 D 1 , etc. through relaxation, which is slightly influenced by temperature. Only when temperature is extremely high, and the vibrational states reach the intersection between CTS and ground state, quenching will occur through nonradiative loss of energy. Such a configurational coordinate model can be used to interpret the temperature dependence reasonably.
5. Conclusion GdVO 4 :Eu 31 has a quenching temperature higher than 600 K. It shows different temperature properties with different excitation wavelengths which originate from different excitation bands. For host-sensitized luminescence, the host efficiency of the absorption and the energy transfer from host to activators is critical to analyze luminescence properties including temperature dependence. The charge-transfer band of Eu 31 has an important effect for Eu 31 excitation, which can be illustrated using a configurational-coordinate model. The latter can be adopted to explain the difference in temperature dependence of the GdVO 4 :Eu 31 luminescence due to different excitations. The study of the GdVO 4 :Eu luminescence temperature dependence is an important issue for both its application and its luminescence mechanism.
Acknowledgements Supported by The National Nature Science Foundation of China (Grant No. 59732040 and 19774053).
References [1] P.A. Studenikin, A.I. Zagumennyi, Yu.D. Zavartsev, P.A. Popov, I.A. Shcherbakov, Quantum Electron (UK) 25 (1995) 1162–1165. [2] A.I. Zagumennyi, T.D. Zavartsev, P.A. Studenikin, I.A. Scherbakov, F. Umyskov, P.A. Popv, V.B. Ufimtsev, Proc. SPIE Int. Soc. Opt. Eng. (USA) 2698 (1996) 182–192. [3] V.A. Mikhailov, Yu.D. Zavartsev, A.I. Zagumennyi, Quantum Electron (UK) 27 (1997) 13–14. ˆ [4] E. Antic-Fidancev, M. Lemaıtre-Blaise, Spectrochim. Acta, Part A 54 (1998) 2151–2156. [5] F.C. Palilla, A.K. Levin, M. Rinkevics, J. Electrochem. Soc. 122 (1965) 776. [6] Z. Qingli, G. Changxin, S. Chaoshu, Chin. J. Luminescence 21 (4) (2000) 353–358. [7] A. Bril, W.L. Wanmaker, J. Broos, J. Chem. Phys. 43 (1) (1965) 311. [8] A. Bril, W.L. Wanmaker, J. Electrochem. Soc. 111 (12) (1964) 1363–1368. [9] T. Kano, Y. Otomo, J. Electrochem. Soc. 116 (1) (1969) 64–68. [10] A.S. Moskvin, M.Y. Khodos, B.I. Kucherenko, Zh. Prikl. Spectrosk. 18 (1) (1973) 54–58. [11] G. Blase, in: B. Di Bartolo (Ed.), Luminescence of Inorganic Solid, Plenum Press, New York, 1978, p. 461.
L
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Temperature dependence of GdVO 4 :Eu 31 luminescence a,b
Bo Liu , Chaoshu Shi a
a,b,c ,
*, Qingli Zhang c , Yonghu Chen b
Structure Research Laboratory, University of Science and Technology of China, Hefei, 230026, China b NSRL, University of Science and Technology of China, Hefei, 230029, China c Department of Physics, University of Science and Technology of China, Hefei, 230026, China Received 17 April 2001; accepted 18 June 2001
Abstract The temperature dependence of the GdVO 4 :Eu 31 luminescence from the Eu 31 5 D 0 → 7 F J transition above room temperature has been studied. The intensity of the luminescence when excited at 313 and 365 nm increases rapidly as temperature rises up to 600 K while the emission intensity at 254 nm only changes a little. The origin of this novel phenomenon is analyzed and discussed by energy transfer from host to Eu 31 in terms of a configurational-coordinate model. 2002 Elsevier Science B.V. All rights reserved. Keywords: Rare earth compounds; Optical materials; Luminescence PACS: 78.55.-m; 78.20. Bh; 78.20. Nv
1. Introduction As laser crystals, GdVO 4 :RE 31 (such as Pr 31 , Nd 31 , Ho 31 , Er 31 , Tm 31 , Yb 31 ) have been extensively investigated [1–4]. Although GdVO 4 :Eu 31 will not be used in laser operations, it is a significant red-emitting material with a main emission peak at 619 nm. The luminescence intensity of GdVO 4 :Eu 31 is in the same order as that of YVO 4 :Eu 31 [5]. Recent research has shown that the emission and excitation spectra depend on doping manners and the sintering atmosphere [6], from which we can understand the process of energy transfer. Additionally, Gd–Eu is also a good physical system to study on energy transfer. Recently, our experiments showed that GdVO 4 :Eu 31 has good temperature properties and a higher quenching temperature than YVO 4 :Eu 31 , so it is very suitable for application in high temperature environments such as high-pressure mercury-vapor lamps. The temperature dependence of the 313 and 365 nm excitation was different from the 254 nm excitation. The purpose of this
*Corresponding author. E-mail address: [email protected] (C. Shi).
article is to study the temperature properties of the GdVO 4 :Eu 31 luminescence and to give some possible explanations for its mechanism.
2. Experimental A polycrystalline sample of GdVO 4 :Eu 31 (10 mol%) was made by reacting stoichiometric proportions of V2 O 5 and Gd 2 O 3 of 99.99 and 99.95% purity, respectively. The nitric acid solution of Eu 2 O 3 was used to dope Eu 31 into GdVO 4 . The mixture was sintered in an air atmosphere at 8008C for 8 h, then the polycrystalline GdVO 4 :Eu 31 was obtained. X-Ray diffraction measurements (XRD) were carried out at room temperature using a D/ Mrax-rA Rotation Anode X-ray Diffractometer with Cu Ka radiation. From the XRD, it is concluded that the sample crystallized well and has the ZrSiO 4 structure, belonging to the space group I4 /amd. The temperature dependence of the GdVO 4 :Eu 31 luminescence was obtained under excitation at 313 and 365 nm from a high-pressure mercury-vapor lamp and 254 nm from a low-pressure mercury-vapor lamp, using suitable filters. The transmission of the filter used in a high-
0925-8388 / 02 / $ – see front matter 2002 Elsevier Science B.V. All rights reserved. PII: S0925-8388( 01 )01711-X
216
B. Liu et al. / Journal of Alloys and Compounds 333 (2002) 215 – 218
pressure mercury-vapor lamp is in the range 300–400 nm in which there are two strong emission lines at 313 and 365 nm. These experiments include emission spectra at different temperatures and emission peak intensities as a function of temperature with different excitation wavelengths. A TC-100U temperature controller with different programs was used for temperature measurement. The emission spectra were measured with an HRD-1 double grating monochromator made by the J-Y Company, France. The excitation spectrum was measured with a Hitachi 850 type fluorescence spectrometer at room temperature.
3. Experimental results
3.1. Temperature dependence of GdVO4 : Eu 31 luminescence excited at 313 and 365 nm The emission spectra at different temperatures above room temperature are shown in Fig. 1. The characteristic emissions of Eu 31 were observed, including those peaking at 608, 616 and 619 nm for 5 D 0 → 7 F 2 transition, at 594 and 598 nm for 5 D 0 → 7 F 1 transition and at 538 nm for 5 D 1 → 7 F 1 transition. Each increases with rising temperature, and the relative intensity of the emission lines remains constant. Fig. 2 shows the emission intensities at 619, 615, 594 and 698 nm as a function of temperature. In the range of 300–600 K, each emission line increases as the temperature rises, especially above 400 K, and there is a rapid increase without intensity saturation up to 600 K. The emission intensity at 600 K is 20 times stronger than that at 300 K.
Fig. 2. The intensity of different emissions of Eu 31 as a function of temperature excited at 313 and 365 nm.
3.2. Temperature dependence of GdVO4 : Eu 31 luminescence excited at 254 nm The characteristic emission excited at 254 nm is the same as that when excited at 313 and 365 nm. The intensity at 619, 698 and 538 nm emissions as a function of temperature is shown in Fig. 3. It can clearly be seen that the emission intensities at 619 and 698 nm decreased as the temperature rises while the intensity at 538 nm increased with rising temperature. The changes are all modest. This is quite different from the dependences observed under excitation at 313 and 365 nm.
3.3. The excitation spectrum of the 619 -nm emission from GdVO4 : Eu 31 at room temperature As shown in Fig. 4, it can be observed that the excited spectrum of the 619-nm emission contains two main
Fig. 1. Emission spectra of GdVO 4 :Eu at different temperatures excited at 313 and 365 nm.
Fig. 3. The intensity of different emissions of Eu 31 as a function of temperature excited at 254 nm.
B. Liu et al. / Journal of Alloys and Compounds 333 (2002) 215 – 218
217
Fig. 4. Excitation spectrum of GdVO 4 :Eu 31 with emission wavelength 619 nm at RT.
excitation bands peaking at about 250 and 310 nm, besides the intrinsic excitation of Eu 31 . The intensity of intrinsic excitation is much weaker than that of the excitation bands at 250 and 310 nm.
4. Discussion Many compounds doped with europium ions such as YVO 4 :Eu 31 , Gd 2 O 3 :Eu 31 , Y 2 O 3 :Eu 31 , GdPO 4 :Eu 31 , have similar temperature properties of luminescence to GdVO 4 :Eu 31 and a high quenching temperature [7–9]. Similar to YVO 4 :Eu, GdVO 4 :Eu belongs to the ZrSiO 4 structure. The Eu 31 ions enter the host lattices of GdVO 4 or YVO 4 and substitute for Gd 31 or Y 31 . Eu 31 and its surrounding thus form a molecular aggregate of symmetry D2d . So many similar properties exist between GdVO 4 :Eu 31 and YVO 4 :Eu 31 . The excitation spectra for both GdVO 4 :Eu 31 and YVO 4 :Eu 31 consist of two main excitation bands peaking at about 250 and 320 nm [7]. Kano et al. [9] reported that for YVO 4 :Eu 31 , the integrated emission intensity excited at 254 nm changes slightly with increasing temperature while the integrated intensity increases rapidly when excited at 313 and 365 nm in the temperature range 100–450 K. Moskvin et al. [10] also reported that the intensity of YVO 4 :Eu 31 luminescence increased rapidly when excited by a high pressure mercury-vapor lamp and reached a maximum when the temperature reached 500 K. For GdVO 4 :Eu 31 , there is a more significant increase without saturation up to 600 K. GdVO 4 :Eu 31 is a typical host sensitizing luminescence material. So its emission intensity and efficiency mainly depend on the host absorption and energy transfer from the host to activators. Concerning the excitation of the Eu 31 emission, a charge-transfer state (CTS) should be considered. For Eu 31 in eight-coordination, the charge-transfer band is in the region from 220 to 270 nm [11]. The band peaking at 310 nm is due to vanadate absorption followed
Fig. 5. Scheme of GdVO 4 :Eu 31 energy levels and transitions.
by energy transfer to activators Eu 31 . In fact, the intrinsic Eu 31 excitation is much weaker than host excitation. Fig. 5 represents a scheme of GdVO 4 :Eu 31 energy levels and transitions. In order to analyse the different temperature dependences under excitation at 313 and 365 nm and at 254 nm, a configurational-coordination model shown in Fig. 6 was proposed. When GdVO 4 :Eu 31 is
Fig. 6. Configurational-coordinate diagram for Eu 31 in GdVO 4 :Eu 31 .
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excited at 313 nm, the excitation energy can be transferred to Eu 31 through VO 43- , which makes Eu 31 rise to its excited states which are lower than its CTS. For excitation at 365 nm, Eu 31 ions are excited to the states 5 D J directly. The Eu 31 can be fed into 5 D J through cascade relaxation according to the order 5 D 3 , 5 D 2 , 5 D 1 , 5 D 0 accompanied by phonon emissions. The time of relaxation between 5 D J (such as from 5 D 1 to 5 D 0 ) is of the order of 10 24 s. Both 313- and 365-nm excitation cannot excite Eu 31 into its CTS directly. Under the excitation of 365 nm, Eu 31 can be excited into the 365-nm level of Eu 31 shown in Fig. 6 and at the same time, form many vibration states whose energy is higher than that of 356 nm due to the effect of temperature. When the energy of vibration states is close to CTS, it can enter CTS more easily. When the temperature rises, it can be fed into CTS of Eu 31 through thermal disturbance. So when the temperature rises, the probability of going from the vibration state of 365 nm level of Eu 31 to CTS will increase. Subsequently it can relax along the parabola of the configurational-coordinate, shown in Fig. 6. During the process of relaxation, the energy can be transferred to 5 D 0 , 5 D 1 , 5 D 2 , 5 D 3 directly. This period is much less than 10 27 s and needs no cascade relaxation from 5 D 3 to 5 D 2 until 5 D 0 . Therefore if CTS acts as middle state, the process of luminescence will be influenced by temperature intensively and causes the enhancement of luminescent intensity when temperature rises. If Eu 31 can enter CTS, the emission from 5 D 0 to 7 F J will become more efficient because it is not necessary to involve 5 D 2 , 5 D 1 , etc. For the 365-nm excitation, Eu 31 cannot be excited into CTS, but can only come into CTS by making use of thermal disturbance. So the efficiency of 5 D 0 emission is temperature-dependent and when temperature rises the emission of 5 D 0 will increase. In the range of measurement, no decrease in luminescence was observed so the quenching temperature is higher than 600 K, which corresponds to the intersection of two parabolas. When excited at 254 nm, Eu 31 ions are directly excited into CTS, then promptly come into lower excited states such as 5 D 0 , 5 D 1 , etc. through relaxation, which is slightly influenced by temperature. Only when temperature is extremely high, and the vibrational states reach the intersection between CTS and ground state, quenching will occur through nonradiative loss of energy. Such a configurational coordinate model can be used to interpret the temperature dependence reasonably.
5. Conclusion GdVO 4 :Eu 31 has a quenching temperature higher than 600 K. It shows different temperature properties with different excitation wavelengths which originate from different excitation bands. For host-sensitized luminescence, the host efficiency of the absorption and the energy transfer from host to activators is critical to analyze luminescence properties including temperature dependence. The charge-transfer band of Eu 31 has an important effect for Eu 31 excitation, which can be illustrated using a configurational-coordinate model. The latter can be adopted to explain the difference in temperature dependence of the GdVO 4 :Eu 31 luminescence due to different excitations. The study of the GdVO 4 :Eu luminescence temperature dependence is an important issue for both its application and its luminescence mechanism.
Acknowledgements Supported by The National Nature Science Foundation of China (Grant No. 59732040 and 19774053).
References [1] P.A. Studenikin, A.I. Zagumennyi, Yu.D. Zavartsev, P.A. Popov, I.A. Shcherbakov, Quantum Electron (UK) 25 (1995) 1162–1165. [2] A.I. Zagumennyi, T.D. Zavartsev, P.A. Studenikin, I.A. Scherbakov, F. Umyskov, P.A. Popv, V.B. Ufimtsev, Proc. SPIE Int. Soc. Opt. Eng. (USA) 2698 (1996) 182–192. [3] V.A. Mikhailov, Yu.D. Zavartsev, A.I. Zagumennyi, Quantum Electron (UK) 27 (1997) 13–14. ˆ [4] E. Antic-Fidancev, M. Lemaıtre-Blaise, Spectrochim. Acta, Part A 54 (1998) 2151–2156. [5] F.C. Palilla, A.K. Levin, M. Rinkevics, J. Electrochem. Soc. 122 (1965) 776. [6] Z. Qingli, G. Changxin, S. Chaoshu, Chin. J. Luminescence 21 (4) (2000) 353–358. [7] A. Bril, W.L. Wanmaker, J. Broos, J. Chem. Phys. 43 (1) (1965) 311. [8] A. Bril, W.L. Wanmaker, J. Electrochem. Soc. 111 (12) (1964) 1363–1368. [9] T. Kano, Y. Otomo, J. Electrochem. Soc. 116 (1) (1969) 64–68. [10] A.S. Moskvin, M.Y. Khodos, B.I. Kucherenko, Zh. Prikl. Spectrosk. 18 (1) (1973) 54–58. [11] G. Blase, in: B. Di Bartolo (Ed.), Luminescence of Inorganic Solid, Plenum Press, New York, 1978, p. 461.