Most people would use a crate,but if your yorkie will be alone from 6:30am until 7pm,I would use a play pen or keep him in a small room (bathroom,kitchen..etc).Iv never liked the idea of crates because I think it would drive me mad if I were a small dog..especially if it was for long hours at a time.I would try keeping him in the bathroom or kitchen.Just sweep the floor to make sure theres nothing they can choke on etc,get any trash cans out of the way (or TP if you decide on the bathroom),and then his things..pee pad,toys,bed,water,food..etc.Also,make sure there are no electrical cords to chew on.Doing this he should be fine.Also,I used to leave the radio on when I was going to be a long time,I think it keeps them company
(just make sure its out of reach).I honestly wouldent recomend a crate for long hours,to me it seems cruel.
They usualy sleep all the time we are out anyway,but its nice for them to have space to move around if they really need too