W . Coughanour, R. S. Roth, a nd V. A. DeProsseThe systems CaO-Ti02 and Zr0 2-Ti 02 were studied by means of solid-sta te reactions and by the observation of fu sion characteristics. The existence of t wo bin a r y co mpound s in the CaO-Ti02 system was con firmed . One co mpound was fo und to exist in the Zr02-1 i02 system. This co mpound , Zr02· Ti 02, has been found to ha ve orthor hombi c sy mm etry wi th t he following pa ra meters at roo m te mperature : a = 4.806 A, b= 5.032 A, c= 5.447 A. Solidsolu tion development was obse rved in t he Zr02-Ti 02 system , bu t not in t he CaO-Ti 0 2 system. Fro m t he d ata o btained , an equilibr ium di agram is suggested fo r each system. IntroductionA study of phase relationships in th e systems CaOTi02 and ZrOz-Ti02 h as been condu cted as a par t of a program of fundam en tal stud ies of cerami c dielect rics . l B oth of these systems have been investigated by prev ious workers. The res ul ts of these investigat ions were ra ther d ivergen t, however , so i t was cons idered essen tial that the systems b e reinvestigated.The number of com po unds proposed fo r th e CaO-T i02 system h as varied from one [1] 2 to three [2]. Some previous studi es of the Zr02-Ti02 system [3,4] h avo ind icated th e a bsence of any compounds in the system and th e presence of part ial solid solu t ions. The possibili ty of the stabili zation of th e tetragonal form. of Zr02 by Ti02 has . also been suggested [5]. Brown and Duwez [6] from X -ray and thermal-ex pa nsion meas urem ents proposed a phase diagram ind icating the comp ound Zr02· TiOz. Their d iagram , although no t suppor ted by fusion-poin t data, is simil ar to th e one determined in the present investigation.The determina tion of the meltin g poin ts of the com po und s, and of the solidus and liquidus temperat uros at various points across the two systems, have s upp li ed data from which a revised equilibrium diagr am h as been constructed for th e systems CaOTi02 and Zr02-Ti02. Sample Preparation and Test MethodsThe following materials were used as th e source of componen ts in th e samples fo r this study: CaOEimer Amend Co. reagen t-grade calcium carbonate of 99.5-percen t purity; Zr02-dense Zr02 of nominal 99-per cen t purity, ob tained from the Ti tanium Alloy Manufacturing Co.; Ti02-highly purified titania of purity over 99.9-per cent, ob tained from the Ti tanillm Division of the N a tional Lead Co.Calculations of weigh t composition wer e m ade to ± 0.0l p ercen t, no correction being m ade for t he p ercentage purity of the r aw materials.I 'rhis study was sponsored by the Office of Ordnance Research, Department oCthe Army.2 :J<'igures in brackets indicate literature references at the end of this paper.

W. Coughanour and V. A. DeProsseThe phase relatio ns in t he syste m :VJgO-TiO, we re studi ed by means of , oli d -phase r eactions between t he co mpone nts and by obse rving t he fu sio n cha racterist ics of s pecimens within t he syste m. The ex isten ce of three binary compounds in t he sys te m was con firm ed . F rom the data obtain ed, an equilibrium diagram for t he syste m is s ugges ted .