What type of visa should we apply for?

Hello,
My husband is a student and is due to go to China to carry out his research at Fudan University for 9 months. I understand that he should apply for a X visa. Me and my 2 young children will be accompanying him and staying for 6 months, but I am not sure what type of visa we should be applying for. If you could provide any clarification, that would be great.
Many Thanks, Tess Tebboth