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High temperature transport processes in lithium niobate
Vol. 7, No. 17
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
point ion model, the interaction between a pair of ions in the vibrating lattice is essentially a Coulomb potential screened by the electrons. It is shown that if the screening is weakly dependent on the electron density in Si, Ge, and a-Sn, then the phonon frequencies Wqj in these crystals scale approximately 2/Ma3Icl~~,as observed where [lqjby isKucher, a dimension[(4e) less =frequency that is independent of the particular material being considered. Evidence is presented in the RPA to support this explanation of the scaling. Received 5 May 1969 Revised 2 July 1969
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a function of time. The diffusion data may be represented by D = 3.03 x 10~ 2/sec. Considerexp (—29.4 Kcal mole~/RT)cm at ion of the Nernst—Einstein relation for oxygen and the variation in conductivity with Li 20 activity indicate that the ionic conduction is caused by transport of lithium ions. Received 27 May 1969 Revised 9 July 1969
9.
THE TEMPERATURE DEPENDENCE OF
HIGH TEMPERATURE TRANSPORT PROCESSES IN LITHIUM NIOBATE
THE SHORT WAVELENGTH TRANSMITTANCE LIMIT OF VACUUM ULTRAVIOLET WINDOW MATERIALS — 1. EXPERIMENT W.R. Hunter, E.O. Hulburt Center for
Paul J. Jorgensen, Stanford Research Institute, Menlo Park, California 94025, U.S.A. and Robert W. Bartlett, Stanford University, Palo Alto, California 94305, U.S.A.
Space Research, U.S. Naval Research Laboratory, Washington, D.C. 20390 and S.A. Malo, Imperial College of Science and Technology, South Kensington, London, S.W.7
The electrical conductivity of single crystal lithium niobate (LiNbO 3) was determined as a function of temperature for various oxygen partial pressures. The electrical conductivity is proportional to P~”~ which can be explained by a defect equilibrium involving singly ionized oxygen vacancies and electrons. Measurements of electrical transport numbers at 1000°K show the electrical conductivity of LiNbO3 to be ionic at one atmosphere of oxygen and electronic at low oxygen partial pressures. Thermoelectric measurements indicate that LiNbO3 at low oxygen partial pressures is n-type and that the concentration of electrons at 1000dI< and in 17/cm3 an atmosphere of 50%CO/50%CO2 with a mobility of 1.7cm2/Vissec. 4 x 10 The diffusion of oxygen in LiNbO 3 was determined as a function of temperature at an oxygen partial pressure of 70 Torr by measuring 018/016 isotope exchange with the gas phase as
The short wavelength transmittance limit or cut-off wavelength, A~0,of LiF, MgF2, CaF2, LaF3, BaF2 , sapphire, synthetic crystal quartz and fuzed quartz has been measured from about 100°Cto about 10°K. Acc, is not a well defined quantity, so for the purpose of this experiment it has been arbitrarily taken as the wavelength where transmittance could just be measured, usually 0.1—0.5%. With one exception ~ shifted to shorter wavelengths as the sample was cooled; the shift varied from about 40A to 80A over the temperature range from 100°C to 10°K, depending on the material, with the largest shift occurring in BaF2 . The exception was LaF3 which showed no measurable change in ~ with temperature. Over the temperature range from 20°C to 100°C the slope A,~withbut temperature for italldecreased, materials was fairly ofconstant, below 20°C approaching zero as the temperature approached 20—10°K.In the case of synthetic crystal quartz, for example, the slope changed from about 0.28 A/°K at room temperature to about 0.055 A/°K at 80°K.
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
point ion model, the interaction between a pair of ions in the vibrating lattice is essentially a Coulomb potential screened by the electrons. It is shown that if the screening is weakly dependent on the electron density in Si, Ge, and a-Sn, then the phonon frequencies Wqj in these crystals scale approximately 2/Ma3Icl~~,as observed where [lqjby isKucher, a dimension[(4e) less =frequency that is independent of the particular material being considered. Evidence is presented in the RPA to support this explanation of the scaling. Received 5 May 1969 Revised 2 July 1969
8.
iii
a function of time. The diffusion data may be represented by D = 3.03 x 10~ 2/sec. Considerexp (—29.4 Kcal mole~/RT)cm at ion of the Nernst—Einstein relation for oxygen and the variation in conductivity with Li 20 activity indicate that the ionic conduction is caused by transport of lithium ions. Received 27 May 1969 Revised 9 July 1969
9.
THE TEMPERATURE DEPENDENCE OF
HIGH TEMPERATURE TRANSPORT PROCESSES IN LITHIUM NIOBATE
THE SHORT WAVELENGTH TRANSMITTANCE LIMIT OF VACUUM ULTRAVIOLET WINDOW MATERIALS — 1. EXPERIMENT W.R. Hunter, E.O. Hulburt Center for
Paul J. Jorgensen, Stanford Research Institute, Menlo Park, California 94025, U.S.A. and Robert W. Bartlett, Stanford University, Palo Alto, California 94305, U.S.A.
Space Research, U.S. Naval Research Laboratory, Washington, D.C. 20390 and S.A. Malo, Imperial College of Science and Technology, South Kensington, London, S.W.7
The electrical conductivity of single crystal lithium niobate (LiNbO 3) was determined as a function of temperature for various oxygen partial pressures. The electrical conductivity is proportional to P~”~ which can be explained by a defect equilibrium involving singly ionized oxygen vacancies and electrons. Measurements of electrical transport numbers at 1000°K show the electrical conductivity of LiNbO3 to be ionic at one atmosphere of oxygen and electronic at low oxygen partial pressures. Thermoelectric measurements indicate that LiNbO3 at low oxygen partial pressures is n-type and that the concentration of electrons at 1000dI< and in 17/cm3 an atmosphere of 50%CO/50%CO2 with a mobility of 1.7cm2/Vissec. 4 x 10 The diffusion of oxygen in LiNbO 3 was determined as a function of temperature at an oxygen partial pressure of 70 Torr by measuring 018/016 isotope exchange with the gas phase as
The short wavelength transmittance limit or cut-off wavelength, A~0,of LiF, MgF2, CaF2, LaF3, BaF2 , sapphire, synthetic crystal quartz and fuzed quartz has been measured from about 100°Cto about 10°K. Acc, is not a well defined quantity, so for the purpose of this experiment it has been arbitrarily taken as the wavelength where transmittance could just be measured, usually 0.1—0.5%. With one exception ~ shifted to shorter wavelengths as the sample was cooled; the shift varied from about 40A to 80A over the temperature range from 100°C to 10°K, depending on the material, with the largest shift occurring in BaF2 . The exception was LaF3 which showed no measurable change in ~ with temperature. Over the temperature range from 20°C to 100°C the slope A,~withbut temperature for italldecreased, materials was fairly ofconstant, below 20°C approaching zero as the temperature approached 20—10°K.In the case of synthetic crystal quartz, for example, the slope changed from about 0.28 A/°K at room temperature to about 0.055 A/°K at 80°K.