Lanthanum modified lead zirconate (PLZT) is a ferroelectric ceramic which possesses high pyroelectric coefficient and a Curie temperature ([T.sub.c]) of about 180[degrees]C [11, 12]; therefore, in the present study, PLZT was used as pyroelectric detector in TWRC configuration.
The resulting PLZT ceramic was used as pyroelectric sensor in the TWRC experimental setup in order to obtain the thermal diffusivity of well-know liquids as distilled water, olive oil, glycerol, and ethylene glycol.
In the present study, the thermal diffusivities of different liquid samples were obtained by using the TWRC with two different PE sensors (PLZT and PVDF) in order to compare their performance.
In order to corroborate the enhancement of the measurements in TWRC configuration, when PLZT sensor is used instead of the PVDF sensor, the thermal diffusivities of other liquid samples (glycerol, ethylene glycol, and olive oil) were obtained by using the same procedure described previously and the results are shown in Table 1 where the obtained thermal diffusivities are compared, using PLZT and PVDF as PE detectors; it can be seen that the [[alpha].sub.s] values obtained with PLZT are near to the [[alpha].sub.s] values obtained with PVDF; however, an increment in the precision can be observed as well as a reduction of the errors.
In this work, a PLZT was used as PE detector in order to obtain the thermal diffusivities of different liquid samples as distilled water, olive oil, glycerol, and ethylene glycol by the TWRC method.
Fischer to Carl, 13 August 1918, TWRC; Ayer and Son's Annual (1914), 1257-1258; N.
15 James Robert Mock, Censorship 1917 (Princeton, 1941), 32; Henry Schmidt, "The Rhetoric of Survival: The Germanist in America from 1900 to 1925," in America and the Germans, 2:211; Resolution of the State Council of Defense, 11 February 1919, TWRC; Luebke, Bonds of Loyalty, 312; Giddings News, 23 August 1918; Texas, House, H.B.
16 Minutes of the Fayette County Council of Defense, 4 July 1918, TWRC; Bruns, "Persecution of German Americans," 115; Giddings News, 23 August 1918; James W.
36, Council of National Defense to the Several State Councils, 21 December 1918, TWRC; R.
Crosby to Carl, 23 December 1918, TWRC; Minutes of the Fayette County Council of Defense, 4 July 1918, TWRC; Resolution of the Texas State Council of Defense, 11 February 1919, TWRC; Council of National Defense, Texas Division Woman's Committee, "Report of Child Welfare Department, Woman's Committee Council of National Defense, Texas Division, April 6, 1918 to June 1, 1919," n.d., TWRC.
20 Fred Huggins to Carl, 10 January 1918, TWRC; Resolution of the Grimes County Council of Defense, n.d., TWRC; Higham, Strangers in the Land, 260.
Lawhon to the State Council of Defense, 18 March 1918, all in TWRC.