Dielectric Properties of Φ(BZT-BCT)-(1−Φ) Epoxy Composites with 0-3 Connectivity

Abstract

Lead free ferroelectric ceramic [0.5[Ba(Zr<sub >0.2</sub>Ti<sub >0.8</sub>)O<sub >3</sub>]-0.5[(Ba<sub >0.7</sub>Ca<sub >0.3</sub>)TiO<sub >3</sub>]]/(BZT-BCT)-epoxy composites with 0-3 connectivity (particles connected in 3 dimensions) were prepared using hand lay-up technique followed by cold pressing for different volume fractions of (BZT-BCT) ceramic powder in the epoxy polymer matrix. The structural, microstructural, and dielectric properties of the composites have been investigated and discussed. XRD studies revealed the presence of both ceramic and polymer phases in the (BZT-BCT)-epoxy composites. SEM studies showed a uniform distribution of ceramic particles in the epoxy matrix, which confirmed the 0-3 connectivity in the composites. Dielectric studies revealed an increase in relative permittivity (<svg style="vertical-align:-3.3907pt;width:12.7375px;" id="M1" height="11.9625" version="1.1" viewBox="0 0 12.7375 11.9625" width="12.7375" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,7.675)"><path id="x1D700" d="M387 375q0 -16 -17 -31t-29 -15q-9 0 -12 13q-13 74 -80 74q-36 0 -61 -24.5t-25 -56.5t24 -51.5t68 -19.5q33 0 47 2l2 -7l-32 -42q-20 2 -54 2q-45 0 -74 -21.5t-29 -60.5q0 -41 28 -65.5t73 -24.5q78 0 145 67l17 -23q-33 -47 -84.5 -75t-111.5 -28q-70 0 -114.5 35.5&#xA;t-44.5 92.5q0 46 38 78t95 45v2q-35 10 -54.5 33t-19.5 52q0 55 53 88.5t122 33.5q67 0 98.5 -23.5t31.5 -49.5z" /></g> <g transform="matrix(.012,-0,0,-.012,7.037,11.762)"><path id="x1D45F" d="M393 379q-9 -16 -28 -29q-15 -10 -23 -2q-19 19 -36 19q-21 0 -52 -38q-57 -72 -82 -126l-40 -197q-23 -3 -75 -18l-7 7q49 196 74 335q7 43 -2 43q-7 0 -30 -14.5t-47 -37.5l-16 23q37 42 82 73t67 31q41 0 15 -113l-11 -50h4q41 71 85 117t77 46q29 0 45 -26&#xA;q13 -21 0 -43z" /></g> </svg>) and decrease in dielectric loss (<svg style="vertical-align:-0.1638pt;width:33.637501px;" id="M2" height="12.4375" version="1.1" viewBox="0 0 33.637501 12.4375" width="33.637501" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,12.162)"><path id="x74" d="M298 36l-68 -35q-25 -13 -42 -13q-98 0 -98 119v290h-69l-4 11l28 29h45v72l65 67l14 -2v-137h113q8 -8 6 -21t-12 -19h-107v-256q0 -96 59 -96q29 0 61 17z" /></g><g transform="matrix(.017,-0,0,-.017,5.332,12.162)"><path id="x61" d="M433 39l-85 -51q-27 0 -47 20q-16 16 -24 44q-5 -3 -24 -16.5t-27 -18.5t-23 -13.5t-25 -12t-19 -3.5q-52 0 -86 36.5t-34 85.5q0 71 81 99q128 43 155 65v17q0 54 -23 83.5t-62 29.5q-28 0 -45 -19t-29 -66q-7 -23 -29 -23q-15 0 -29 13t-14 30t31 40q25 19 68.5 40.5&#xA;t81.5 29.5q49 0 82 -27q45 -39 45 -123v-185q0 -60 35 -60q18 0 36 11zM275 84v156q-12 -6 -49 -23t-41 -19q-31 -14 -46 -31t-15 -43q0 -35 22.5 -55.5t48.5 -20.5q19 0 42 10.5t38 25.5z" /></g><g transform="matrix(.017,-0,0,-.017,12.659,12.162)"><path id="x6E" d="M524 0h-209v26q44 5 55 18t11 65v167q0 114 -91 114q-50 0 -109 -51v-235q0 -50 10 -61.5t55 -16.5v-26h-217v26q51 5 62 17t11 61v206q0 47 -9.5 58.5t-50.5 19.5v23q82 15 139 40v-79l67 47q47 30 83 30q60 0 94.5 -40t34.5 -112v-193q0 -50 10 -61.5t54 -16.5v-26z&#xA;" /></g><g transform="matrix(.017,-0,0,-.017,24.779,12.162)"><path id="x1D6FF" d="M494 514l-10 -15q-56 76 -106.5 117t-110.5 41q-45 0 -45 -30q0 -28 109 -152q59 -68 86 -118.5t27 -107.5q0 -62 -29.5 -119.5t-86.5 -96.5q-64 -45 -138 -45q-76 0 -121.5 53t-45.5 136q0 74 40.5 135t98.5 95q43 26 87 42q-40 59 -57.5 92t-17.5 62q0 46 39 77.5&#xA;t90 31.5q54 0 97.5 -35.5t65 -78.5t28.5 -84zM359 234q0 84 -90 191q-47 -17 -74 -47q-81 -89 -81 -200q0 -71 32.5 -109.5t72.5 -38.5q47 0 80 33t46.5 77.5t13.5 93.5z" /></g> </svg>) in the composites with the increase in the volume fractions of the ceramics up to 20&#x25;. This can be ascribed to the increase in density of the composites and dielectric properties of the epoxy polymer. At room temperature (RT) and at 1&#x2009;kHz frequency, 0.2(BZT-BCT)-0.8(epoxy) composite showed the highest relative permittivity <svg style="vertical-align:-3.3907pt;width:60.237499px;" id="M3" height="16.4125" version="1.1" viewBox="0 0 60.237499 16.4125" width="60.237499" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,12.138)"><path id="x28" d="M300 -147l-18 -23q-106 71 -159 185.5t-53 254.5v1q0 139 53 252.5t159 186.5l18 -24q-74 -62 -115.5 -173.5t-41.5 -242.5q0 -130 41.5 -242.5t115.5 -174.5z" /></g><g transform="matrix(.017,-0,0,-.017,5.944,12.138)"><use xlink:href="#x1D700"/></g> <g transform="matrix(.012,-0,0,-.012,12.912,16.212)"><use xlink:href="#x1D45F"/></g> <g transform="matrix(.017,-0,0,-.017,18.562,12.138)"><path id="x29" d="M275 270q0 -296 -211 -440l-19 23q75 62 116.5 174t41.5 243t-42 243t-116 173l19 24q211 -144 211 -440z" /></g><g transform="matrix(.017,-0,0,-.017,29.153,12.138)"><path id="x223C" d="M548 311q-21 -57 -59 -94t-89 -37q-53 0 -128 52q-55 38 -84 38q-39 0 -70.5 -23t-45.5 -60l-32 12q21 57 59 94t89 37q53 0 128 -52q55 -38 84 -38q39 0 70.5 23t45.5 60z" /></g><g transform="matrix(.017,-0,0,-.017,43.857,12.138)"><path id="x33" d="M285 378v-2q65 -13 102 -54.5t37 -97.5q0 -57 -30.5 -104.5t-74 -75t-85.5 -42t-72 -14.5q-31 0 -59.5 11t-40.5 23q-19 18 -16 36q1 16 23 33q13 10 24 0q58 -51 124 -51q55 0 88 40t33 112q0 64 -39 96.5t-88 32.5q-29 0 -64 -11l-6 29q77 25 118 57.5t41 84.5&#xA;q0 45 -26.5 69.5t-68.5 24.5q-67 0 -120 -79l-20 20l43 63q51 56 127 56h1q66 0 107 -37t41 -95q0 -42 -31 -71q-22 -23 -68 -54z" /></g><g transform="matrix(.017,-0,0,-.017,52.016,12.138)"><path id="x34" d="M456 178h-96v-72q0 -51 12.5 -62.5t72.5 -16.5v-27h-256v27q65 5 78 17t13 62v72h-260v28q182 271 300 426h40v-407h96v-47zM280 225v295h-2q-107 -148 -196 -295h198z" /></g> </svg>. For the prediction of the effective dielectric constant of the composites, the experimental data were fitted to several theoretical equations. Effective medium theory (EMT) model and Yamada models were found to be useful for the prediction of the effective dielectric constant of studied composites.