| || Guest Editorial
Author : Pran Kishan;Prakash, Chandra
Source : Defence Science Journal ; Vol:57(3) ; 2007 ; pp
| || Modified Lead-zirconate-titanate for Pyroelectric Sensors
Author : Thakur, O. P.;Singh, J. P.;Prakash, Chandra;Pran Kishan
Source : Defence Science Journal ; Vol:57(3) ; 2007 ; pp 233-239
Subject : 681.586 Sensors
Keywords : PZT;IR detectors;Ceramic materials;Lead-zirconatetitanate systems;Pyroelectric sensors;Sensors
Abstract : Pyroelectric sensors based on ceramic materials have found applications in IR detection in defence and civil systems. To develop suitable ceramic material for IR detector applications, a modified PZT system with compositional formula Pb1-xSmx(Zr0.58Fe0.18Mn0.02Nb0.2Ti0.02)O3 where 0 £ x £ 0.025 was synthesised by conventional solid state reaction method. The materials were characterised for their properties like dielectric and pyroelectric coefficient. Hysteresis loop was recorded at room temperature. The sample with 2 mole per cent samarium (Sm) substitutions was found to be more promising for sensor application based on its high material's figure of merit (FOM). Sensors fabricated with this material were integrated with FET amplifier. The devices configured with compensating element were evaluated for different chopping frequencies. The value of material's FOM, FD, and detectivity, D*, were determined from measured parameters and were, 3.6 x 10-5 Pa-1/2 and 2 x 108 cmHz1/2/W, respectively.
| || Effect of Sintering Temperature on Structural and Piezoelectric Properties of PNN-PZT Ceramics
Author : Mahajan, Sandeep;Thakur, O. P.;Prakash, Chandra
Source : Defence Science Journal ; Vol:57(1) ; 2007 ; pp 23-28
Subject : 66 Chemical Technology
Keywords : PNN-PZT ceramics;Piezoelectric properties;Dielectric properties;Sintering temperature;Piezoelectric ceremics;Piezoelectric materials;Mechanical activation;Perovskite phase
Abstract : Sintering temperatures affect the structural and piezoelectric properties of PbNi1/3Nb2/3- PbZrO3-PbTiO3 system considerably; therefore the effect has been studied on mechano-chemically processed powder. This process involves activating mixed oxides of PbO, NiO, Nb2O5, ZrO2 and TiO2, and in the present study, calcination steps at an intermediate temperatures were skipped which are usually required in conventional solid state reaction methods and chemical routes. Single-phase formation was confirmed from XRD patterns which shows rhombohedral structure at higher sintering temperature. Investigations of the microstructure indicate almost linear increase in grain size from 0.98 m to 2.56 m when the sintering temperature was varied from 1050 oC to 1150 °C. A high value of planar coupling factor (kp) = 67 per cent and piezoelectric charge coefficient (d 33 ~ 750 pm/V; (as determined from strain versus electric field curve at low field) were obtained for the ceramic specimens sintered at 1100 °C. The maximum strain was observed ~ 0.21 per cent at 40 kV/cm applied field for the sample sintered at 1100 °C for 4 h.