How do I transfer my contacts from my sony xperia z phone to my ipad contacts

If you want to transfer your mobile contacts in your ipad, then i have another solution for your issue, first you can save your mobile contacts in vcf format and transfer your ipad, after complete you transfer you can use vCard Export Import software to save your vcf contacts in outlook format.
More Info :- https://www.completeconverter.com/outlook-vcf-export-import/

Here's a guide about How to Transfer Contacts from Android to iPhone. It's also available for iPad.

On your Sony Xperia Z phone, go to contacts list, click on the bottom right button with 3 dots icon, select 'Export contacts'. The contacts will be saved as a 'vcf' file in the location you select. The vcf file is the standard 'vCard' format used by many phones and apps. You can then import your contacts in the vcf file to your ipad.
https://discussions.apple.com/thread/4619772?tstart=0
http://www.ipadforums.net/threads/how-to-import-vcf-file-into-address-book.23905/