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Evaluation of pressure derivatives of bulk modulus of NaClxBr1 − x crystals
Infrared Phys. Technol.Vol. 36, No. 3, p. 741, 1995
Pergamon
Copyright ~ 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 1350-4495/95 $9.50 + 0.00
1350-4495(94)00038-7
RESEARCH NOTE E V A L U A T I O N OF P R E S S U R E D E R I V A T I V E S OF B U L K M O D U L U S OF NaCI~Br,_ ~ C R Y S T A L S B H A N U P. S H A R M A , ~ S. C. GOYAL, t R. P. G O Y A L 2 and M A N I S H JAIN" LDepartment of Physics, Agra College, Agra and -'Department of Physics, St John's College, Agra, India
(Receired 26 April 1994) Abstract--The present paper deals with the evaluation of pressure derivatives of NaCI, Brt _ ~ crystals from their elastic constant data at 0 K and 300 K.
THEORETICAL
BACKGROUND
The recently developed theory to evaluate the Moelwyn Huggesh parameter, (C~), i.e. the pressure derivative of the bulk modules") has been applied to NaCI-NaBr mixed alkali halides with different compositions at 0 K and 300 K. The input data has been taken from Lewis et a l : 2~ and Roberts and Smitht3~ and are reported in Table 1. The calculated values of CI for different compositions of NaCI-NaBr, both at 0 K and 300 K are reported in Table 2. The results show that there is an increasing trend in the values of C, with the decrease in percentage of NaBr and for each composition the values obtained at 300 K are higher than that at 0 K. Table 1. Input data C , x 0" dyne cm-2 Crystals NaCI NaBr
Ct., x 10" dyne cm--'
C.t x 10tt dyne cm-"
C,,2 x l0 N dyne cm- '-
Ct:~ x I0 't dyne cm-2
0K
300 K
0K
300 K
0K
300 K
0K
300 K
0K
300 K
5.733 4.80
4.585 3.704
1.123 0.986
1.264 1.066
-91.096 -74.7
-76.438 -59.598
-3.307 -3.16
-5.283 -4.643
2.290 1.933
2.697 2.220
Table 2. Calculated values of C, C, Crystals
0K
300 K
NaCloBr z NaClo. I Brog NaClo.2 Br0s NaCIo ~Br0: NaCl0.4 Br0.6 NaCIo.~Bro.5 NaCIo6 Br0.4 NaClo. 7Br0.3
4.421 4.423 4.425 4.428 4.430 4.432 4.434 4.436
4.743 4.750 4.757 4.765 4.772 4.779 4.786 4.793
NaClo. s Bro.., NaCIo.9 Bro.i NaCI IBr o
4.439 4.441 4.443
4.801 4.808 4.815
REFERENCES i. B. P. Sharma. S. C. Goyal and R. P. Goyal, Infrared Phys. Technol. 35, 59-61 (1994). 2. J. T. Lewis, A. Lehoczy and C. V. Bdscove, Phys. Rev. 161, 877-87 (1967). 3. R. W. Roberts and C. S. Smith, J. Phys. Chem. Solids 31, 619 (1970). 741
Pergamon
Copyright ~ 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 1350-4495/95 $9.50 + 0.00
1350-4495(94)00038-7
RESEARCH NOTE E V A L U A T I O N OF P R E S S U R E D E R I V A T I V E S OF B U L K M O D U L U S OF NaCI~Br,_ ~ C R Y S T A L S B H A N U P. S H A R M A , ~ S. C. GOYAL, t R. P. G O Y A L 2 and M A N I S H JAIN" LDepartment of Physics, Agra College, Agra and -'Department of Physics, St John's College, Agra, India
(Receired 26 April 1994) Abstract--The present paper deals with the evaluation of pressure derivatives of NaCI, Brt _ ~ crystals from their elastic constant data at 0 K and 300 K.
THEORETICAL
BACKGROUND
The recently developed theory to evaluate the Moelwyn Huggesh parameter, (C~), i.e. the pressure derivative of the bulk modules") has been applied to NaCI-NaBr mixed alkali halides with different compositions at 0 K and 300 K. The input data has been taken from Lewis et a l : 2~ and Roberts and Smitht3~ and are reported in Table 1. The calculated values of CI for different compositions of NaCI-NaBr, both at 0 K and 300 K are reported in Table 2. The results show that there is an increasing trend in the values of C, with the decrease in percentage of NaBr and for each composition the values obtained at 300 K are higher than that at 0 K. Table 1. Input data C , x 0" dyne cm-2 Crystals NaCI NaBr
Ct., x 10" dyne cm--'
C.t x 10tt dyne cm-"
C,,2 x l0 N dyne cm- '-
Ct:~ x I0 't dyne cm-2
0K
300 K
0K
300 K
0K
300 K
0K
300 K
0K
300 K
5.733 4.80
4.585 3.704
1.123 0.986
1.264 1.066
-91.096 -74.7
-76.438 -59.598
-3.307 -3.16
-5.283 -4.643
2.290 1.933
2.697 2.220
Table 2. Calculated values of C, C, Crystals
0K
300 K
NaCloBr z NaClo. I Brog NaClo.2 Br0s NaCIo ~Br0: NaCl0.4 Br0.6 NaCIo.~Bro.5 NaCIo6 Br0.4 NaClo. 7Br0.3
4.421 4.423 4.425 4.428 4.430 4.432 4.434 4.436
4.743 4.750 4.757 4.765 4.772 4.779 4.786 4.793
NaClo. s Bro.., NaCIo.9 Bro.i NaCI IBr o
4.439 4.441 4.443
4.801 4.808 4.815
REFERENCES i. B. P. Sharma. S. C. Goyal and R. P. Goyal, Infrared Phys. Technol. 35, 59-61 (1994). 2. J. T. Lewis, A. Lehoczy and C. V. Bdscove, Phys. Rev. 161, 877-87 (1967). 3. R. W. Roberts and C. S. Smith, J. Phys. Chem. Solids 31, 619 (1970). 741