to a high temperature load reliability test as follows a dc voltage of 400 v was applied to each sample at 175 u00b0 c to measure the change in insulation resistance with time in the high temperature load reliability test when the insulation resistance r reached 10 6 u03c9 or less it was determined to be a failure the mean time to failure in each sample was determined table 2 shows the results for the purpose of evaluation of each of samples 1 to 49 for heat generation during the application of high frequency alternating current a signal voltage of 1 77 kvrms mm at 300 khz was applied to each of samples to measure the dielectric loss tan u03b4 table 2 shows the results from the results shown in table 2 among samples 1 to 6 for investigating the influence of the ratio m of ba to ti ba ti it was found that each of samples 2 to 5 which were within the range of the present invention 0 990 u2266 m u2266 1 050 had high reliability even when operated with high voltage direct current or high frequency high voltage alternating current from the resulting properties described as follows a dielectric constant u03b5 of 300 or more was ensured the dielectric loss tan u03b4 was 0 5 or less at 1 khz and 50 vrms mm the resistivity u03c1 was 10 11 u03c9 m or more the mean time to failure mttf was as long as 100 hours in the high temperature load reliability test 175 u00b0 c dc field strength 40 kv mm.